Below are just a few of the many positive reviews and comments that have been posted on forums or emailed to me directly.

Kevin — Canada

If I was going to walk into a hifi shop looking to purchase a well built, well designed and fine sounding reference grade Single Ended Class ‘A’ Pentode amplifier I would easily be expecting to pay several thousand dollars here in Canada. To my surprise actually, once I built the well thought out Spud Amp kit with its top notch parts and very clear instructions, I had actually built a reference grade tube amp, for quite a bit less, and It puts a smile on my face immediately every time I use it!

I’ve used this amp on two different speakers, one 97dB efficient the other 90dB. The 90dB DIY Tabaq (a wide band speaker) responds very well hooked to the Spud either by itself or hooked up through a quality preamp. My Spud amplified system sounds reference grade to me with deep and wide stage, instruments well defined, highs crystal clear, and enough bass, the mid range and vocals are stunning with this amp. If I hook it to my 97dB with 8 inch drivers (wide band speakers) I am rewarded with even more of this tube goodness. Jerry has provided us audiophile’s or even non-audiophile folks who love music, and good sound with a true gem, one that can easily stand up to the more well known ‘flea watt’ SE amps out there IMHO, and provide equal or perhaps even better performance, and especially for what he asks for it. He’s willing to help out if needed, answers questions in a timely manner so pretty much first rate customer service. Nothing to lose and a whole lot to gain is what I found.

Cedric — Mississippi

Thank you for an amazing amp. Wonderful! I’ve listened to a mix of jazz, country, pop, tv…..old music, new music….Glen Campbell is alive and well, singing at his best via the Spud.

Peter — Massachusetts

I wanted to thank you again.  I put the kit together this weekend.  It took about 5-6 hours total.  Your instructions were excellent!  I have been very comfortable for a few years working on speakers.  Your kit has given me a new found comfort with my broader soldering skills.

Stan — Washington

I’ve been anxious to send you my commentary on the Spud, but I wanted to give it fair burn-in time. I’ve put about 20 hours on the amp using the stock Jan tubes. Toward the end of that period, I did some A/B testing with various amps and speakers.

TEST 1: Spud going to MarkAudio Alpair 10.3 drivers in a ported bookshelf enclosure with no crossover. I wanted to hear the Spud in a minimalist configuration so I hooked up these full-rangers. Honestly, I didn’t expect much with 88 dB efficient speakers. Still, the Spud did better than I expected. At about 60 percent of the volume range, the output was loud enough for pleasant critical listening. (I suppose I could have pushed the amp harder, but I didn’t want to come anywhere near clipping.)  I never thought of the Alpairs as being particularly detailed, but the Spud managed to squeeze out delicate subtleties, particularly in the highs, that I haven’t before with these speakers.  Female vocals are well fleshed-out without being bloomy or saccharine.  Typically, I get bored at low volume levels if the resolution is low. The Spud definitely held my attention. The Spud with the Alpairs would actually be a viable setup in an office or bedroom, where you don’t need to rattle the windows.

TEST 2: Spud versus Class-D amp going to JBL 2445J compression drivers operating at 800 Hz to 7 Khz in a three-way configuration. These 111 dB efficient horns are brutally revealing.  They buzz or hum with every other tube amp I’ve used.  The Spud is dead quiet when not passing a signal.  Setting the volume to about 30 percent drives the JBL’s to robust levels (where my wife is telling me to turn it down).  The system could play much louder, but I’d get in trouble with the neighbors.   The Spud / JBL combo is heavenly! The horns really show what the Spud can do.  As with the Alpairs, the horn sound is delicate, quick, and subtly textured.  Instruments and voices are positioned precisely in space.  Compared to the Class-D amp… well, there is no comparison. The Class-D amp sounds hard-edged and downright unpleasant with the horns.

TEST 3: Spud versus EL34 push-pull monoblocks going to JBL 2445J compression drivers operating at 800 Hz to 12 Khz in a two-way configuration.  For this test, I disabled the tweeters but kept the JBL 2226H bass drivers (50 to 800 Hz) powered by an Anthem solid-state class A/B amp. Of all the amps I own, the custom EL34 monoblocks are the closest in tone to the Spud. The EL34’s have a fine-grained, liquid sound that matches well with the JBL horns. Still, the Spud won out in a head-to-head comparison. The Spud sound is even more refined. There is subtle inner detail that I don’t get with the EL34’s. Bongos and snare drums, for example, are no longer monotone. Additionally, the Spud eliminates a subtle metallic sheen that was present with the EL34’s. I thought this sheen was some digital nastiness coming from digital front end (MiniDSP Nano Digi / Schiit Audio Modi 3), but it turns out this was distortion from the EL34’s.  The Spud is simply less fatiguing while being more detailed. That’s quite a trick!

These tests remind me of my early years with hifi. Back in the late 80s, I bought my first CD player: an 8-bit Denon. I thought that thing sounded wonderful. It seemed so sharp and clear. Then I heard a high-end turntable. At first, I was underwhelmed by the analog sound. It seemed soft in comparison. It took me some time to realize that the softness wasn’t fuzziness, but rather an absence of hard-edged distortion. There was a world of subtle detail in quality analog playback that I was missing with my harsh digital source.  That’s how it is with the Spud. I knew I had something special but the significance didn’t really hit me immediately.  It’s hard to characterize the Spud sound because it doesn’t add much of a sonic signature. It simply reveals without adding distortion. Wow, such a joy!

Thanks, Jerry, for making a quality amplifier available at a reasonable cost!  I’m happy to support an innovative American designer.

Spencer — U.K.

Jerry was a pleasure to deal with from start to finish. Responded quickly to my many mails, and gave helpful advice to get the right look for what I was after for my Spud. Packing from USA to UK was thoughtfully done with many layers of card and bubblewrap to protect the precious cargo!

I’ll give it another week of messing and swapping around, I’m using it at the moment with Kralk Audio BC30 bookshelf speakers on stands which are 90db/1m. On paper they are not ideal for the output of the Spud but give a good account of themselves with room filling sound once the amp is warmed through. My listening room is 5m sq.

Impressions last night- bass is surprisingly good and goes low when required even with my ‘unsuitable’ speakers. Particularly enjoyed Pat Metheny collection on vinyl which comes across more detailed than usual whilst retaining that valve ‘rightness’ of air and space. Cliché but found myself listening to whole albums rather than cherry picking tracks. Amp is certainly revealing, clean, clear and fast dynamics. I also like the minimalist industrial look, the solid build quality, and lack of fussiness. Also of course electricity consumption is low too. Going to borrow some 93 and 95db/1m speakers from a dealer I know so looking forward to hearing the Spud with those.

Paul — Ohio

“I received the amplifier early this afternoon and, after a warm-up period, have been listening with pleasure until now.  It is on the way to becoming my favorite amplifier.  I am particularly pleased about how the instruments are distinct from each other and correctly positioned. I’m happy with the silver color and delighted with the performance of the amplifier. I was a bit surprised that I could hear the difference between the Spud and the amp I had been using so easily. I particularly noticed that Spud delivered more detail. I’m enjoying replaying my favorite CDs and hearing them how good they can sound! Thanks again for the extra effort and time you put into this project.”

Randy — Kentucky

“I placed a class A/B sand amp in the system, and while it was dead quiet at any setting of the volume control, the musicality was severely lacking compared to the Spud. What was most amazing to me was that the 50 watt per channel sand amp produced only a fraction of the bass that the “little” Spud amp produced.

I’m not sure if it is due to the single gain stage or something else, but the Spud is easily one of the most musical and involving amplifiers that I have ever heard ….. at any price. It is coherent beyond belief.  The Betsy 8″ full range drivers in my basic speakers are only 92.5 DB efficient, but having no crossover components they play plenty loud with the Spud in my 16′ x 26′ room.  I seriously think that if more people could hear what I’m hearing right now you would not be able to keep the Spud in stock.”

Kevin — Pennsylvania

“I have quite a few amps, mostly Decware,and one Bottlehead Stereomour 45 using the 45 tube which is the closet I’ve found in sound to the Spud amp, pound for pound the Spud rules. I’ve done some tube rolling and found the Tung Sols my favorite, very open in my 9×13 room, don’t listen very loud, but turned the volume to 11 o clock today. Stunning!

I can tell you, maybe I’m hearing Mr. Brubeck as good as he gets, stunning!!!. Another, ‘have to go through my collection of CD’s again’ days. This amp has already embarrassed some other amps I own, all in the 2 to 6 watt range……..just so you know! 

Man this amp is so easy to listen to. Vocals may be the best I’ve heard. I listen to Joni Mitchell, Patti Barber, and Stevie Wonder, just so open and understandable., very happy with this amp.”

Brandon — Texas (repaired his modified / non-functional Spud)

Brandon did what many people do with their Spuds. Being excited at the sound quality from such a modest circuit, he spent multiples of the kit cost on upgraded components. Unfortunately, things didn’t work out as planned, so he sent it back to me to get things straightened out. Below are his comments as well as before and after pictures.

“The SPUD sounds wonderful. The layout looks so much cleaner and the new tubes sound very sweet. I just added some BCS to my Dayton Audio ps220-8, and the combination with the Spud is really sounding great. In this day and age to find someone who can do quality work with tube amps and be a true professional is rare and awesome! Thanks again Jerry.”

Bruce — Illinois

“Hey Jerry, Put my Spud Amp together yesterday afternoon. WOW! What a marvelous little amp.  The instructions and photos were excellent. The construction sequence was right on. Took a little over four hours to put together, checked my circuit and connections three times, then… holding my breath and crossing my fingers… flipped the power switch and was greeted with sweet, wonderful music!  🙂  My amp is dead black silent with the volume turned all the way up.
Thank you again for making this wonderful amp kit available. It’s really sweet!!”

Andy — Australia

“Dear Jerry,  I today finally got to unpack the Spud and plug it in. What wonderful care you took with the packaging. It was first rate – very professional. And the wonderful selection of tubes – Amperex long plates – how lovely.  I popped those in straight away – it was the green & yellow packaging calling to me… So far I have been happily listening for several hours, and with each hour the Spud is warming to its task and sounding every sweeter.

Externally it is much improved over the one Ricky built me. Very professional indeed. Fit and finish is first rate.  Sound wise – well I am sure that there is a “better” 2-3 wpc flea watt SE amp out there, but I am so very content with the Spud you built for me I certainly don’t feel any need to find out. Bass is much improved over the original, mids are glorious and the tone and timbre is very, very sweet indeed.

This is a seriously good little amp.”

James — Scotland

“Jerry, This is without a doubt the best value amplifier I have ever owned. I cannot compliment it highly enough. And this is before I’ve heard it paired with suitable speakers! I have a few pairs of speakers that could be magical with this amp: Loth-X BS1 (94dB), Tannoy Little Red Monitor (92-94dB-ish) & Fostex FE207E with Eminence Alpha 15A open baffles. All of these are far better suited (on paper) and should let the little spud shine.”

Dan — California

“Going from the Accurian to the spud was a nice improvement. There is nothing harsh about this amp and the detail is a sizable step up. My favorite part about it is the low noise. I always had some hum issues in this system, more so with the Accurian, but now there is none. My Denon tape deck always had a pronounced hum, but it’s all gone! I didn’t expect that from an amplifier change, but it’s true. Even though this is just a couple watt amp, it still has bass.”


“One of the noteworthy things about this particular record is the quality of the vocal recordings. Steely Dan is known for their ultra clean voicing . On Aja they are tight and their musicianship clearly shows.

The spud amp handled everything with ease. Tempo , punctuation and the blend of horns , voices, guitars move in tight coordination.  I immediately felt like the Spud amp presented this material in a cleaner and more open manner than my own amp could? This was immediate and came as a bit of a surprise to us.  This amp can do dynamics but it can also do subtleties equally well. Small inflections in the way words are used to paint pictures in my mind, Becker and Fagen had definitely found their groove by the time Aja was released and I spent an evening revisiting this LP on the Spud….I loved it back in 77 and amazingly still do today.

You have done a great Job here Jerry… Well done. I was initially concerned that I would have a hard time really recommending this amp. I mean, how good could it possibly be for so little money?

I am very happy to fully recommend this to anyone willing to give it a go. I will vote with my wallet, and I don’t pry that thing open for just any piece of audio gear. I am not in big hurry to return this and already think of it as mine. That’s a good sign.”

Marlon —Michigan

“The Spud has no hum, no clicks, and no pops. It is unassuming, quiet, and very easy to listen to. You hear what there is to hear, no more no less. It will not blow the windows out of your house, but it will drive many speakers to a very reasonable listening level.

I have done nothing but listen to music in my free time. I am like a little kid in the candy store. The Mrs. insists I am spending too much time in the dungeon. (of course there is Guinness in the dungeon) I have rediscovered a lot of old friends and am hearing them unveiled for the first time. I am truly amazed at what I’ve been missing.
I dug out the old Adcom amp and hooked it up. It will play louder, but it has no where near the sound stage or clarity of the Spud. That is the Spud’s strong suite. It recreates a musical experience that you can believe. With the lights turned down low the tubes have a glow that is almost seductive.

Thanks Jerry for reminding me how wonderful stereo can be.”