Harley Benton GPA-400

I was a bit hesitant about buying this, Class D, very inexpensive :S But Im glad I did...

Where to start.. Class D amps.. So amp's come in basically 3 types, Tube, Solid State, and Class D. Tube amps have that nice warm tone and gorgeous sounding harmonic distortion, breakup and compression, plus there loud for the watts, but unfortunately cost a fortune. Solid State amps tend to just have raw power and balls once you get up there in the watts, but sound a bit sterile compared to tubes. Class D or digital amps always sound incredibly detailed but cold and sterile to my ears, they tend to put out what you put in without warming anything up or rounding off the bad edges. Also 200 Watts Class D is volume wise about the same as a 30-50 watt tube amp. But as this was for a second guitar rig using some preamps, a G Major FX and a Harley Benton 2x12 Vintage Cab I already owned I didn't want to be shelling out $600-$1000+ on a tube amp, well not at the moment.

Initially I had some problems dialing in a good tone, I think the amp probably needed some run in time to take out a little new amp harshness, and while it didnt sound like a cheap $200 combo when I had a solid state preamp hooked up it, it wasn't doing it for me it tone wise. Solid State preamp and Class D power amp, probably not a good way to go :(

Next up I hooked up a 20 year old Digitech tube preamp, with a bit of EQ tweaking and a OCD clone as a boost I was happily rocking out thinking this sounds pretty good.

Then 2 days ago the AMT SS-10 I ordered turned up. OMG, chimey cleans, gorgeous slight blues breakup, and the crunch / high gain have a great tube compression, and it sounds almost as if there's some power tube breakup and sag going on in the tone. I was in guitar nirvana gurning away like an idiot. After I finished playing Van Halen's "Panama" solo I thought "damn my playing doesn't usually sound that good".

So there you go.. Class D... **** in = **** out, great tone in will equal great tone out. Very transparent and it's not going to hide or warm anything up.

A couple of other things...

* I did A/B it against a blackstar HT5 power stage a few weeks back and the HT5 sounded flat and muddy in comparison.
* It's not hugely loud. I dont know if it would run stereo 4x12 cabs at gig volume, but in bridged mode it should be fine for a single 4x12.
* What's with the dodgy cheap knobs Thomann? It feels like they are glued on too :(
* The tone pot values are a bit too sensitive as well, 10 to 2 o'clock is about all that's usable.
* If you're thinking about getting one of these.. I did try running the 2x12 cab in stereo , but I was getting some weird phase cancellation, probably due to stereo FX.
* Very light.
* Runs cold.
* If you have a high end ( or new model ) modeler this would probably work very well to, unfortunately I don't have any good modeling gear anymore to test with.

I was planing on replacing this with a 20 Watt tube amp when I had the cash, but if my feelings about the ATM don't change, and I don't end up putting the AMT in my main rig, I don't think I'll bother... Great inexpensive power amp if you have a good front end \m/

This guitar power amp deserves 5 stars if I were to evaluate the amp on its own. However, to my shock and awe, when I opened the box, there was a second hand, B-stock or reconditioned unit inside. How do I know? The unit was not wrapped in plastic, the on/off switch was still on and I could see fingerprints, dust and even a few scratched on the top of the unit.

I plugged it in never the less to see whether it was operational before contacting Thomann. I'm pragmatic when it comes to ordering goods from the other side of the planet. Thomann offered a discount which I accepted, including a 3-year-warranty. But it was disappointing that Thomann's warehouse didn't appropriately mark this amp for what it was: used.

Had the power amp sounded crap, I may have actually sent it back but this amp sounds amazing with my Hotone Ampero which I run through a Behringer Ultragain Pro, into this power amp and then into original 1970's greenbacks in stereo.

Before the GPA-400, I ran my Ampero through an LD Systems XS200. It sounded harsh, fizzy and sterile. When running through the power amp stage of my Laney IRT60-H, it sounded better but still fizzy. The GPA-400 hits the mark. It sounds great, whether because it's broken, bad quality or intended by design, it takes the fizzy and harsh trebles away. The presence controls are perfectly calibrated to take even more fizziness out of the signal and the resonance controls are also useful in dialing out flabby sub tones (or dialing them in if you're into djenting). A standard transistor power amp can't do that. This one can.

Overall, it makes my Ampero sound as if it's going through a $1,500 valve power amp. Gutsy, percussive yet soft. A bonus is that it's well built and light. Very light. Not sure whether that's because of a light weight transformer or not. The on/off switch is fine and I'm not fussed about the plastic knobs of the pots. The pots, by the way, are perfectly OK.

The GPA-400 has everything you need from a power amp, especially if you carry it around a lot. At only 3kg, it is so light that it makes travelling to gigs super easy.
There are two channels, each with two speaker connections (jack plugs), so simple and straight forward. The resonance and presence are effectively tone controls, similar to bass and upper mid - I know electronics experts will cringe about this description, but that's pretty much how they work. They can be quite handy for balancing up the tone of slightly different speaker boxes.
There is a push-button mute switch on the front, signal indicators and red clipping LEDs. I never got these to light up, because it is so devastatingly loud, I was frankly too scared.
The sound is clean, really really clean and the high frequencies can be a little bit shrill, but this can be mostly accommodated by EQ in the pre-amp.

So to summarise, a cheap, sturdily built, very light, tremendously loud power amp. It will not sound like an over-driven valve power stage (which will weigh ten times as much), but it will accurately reproduce anything your amp modelling effects unit delivers to it.
For the price, this is an excellent buy.

I bought this amp to fit in my rack with my Line6 Helix and its just perfect. It weighs hardly anything, runs cool and is plenty loud enough for a thrash metal band! I use it live though my Marshall 4x12 and its great.

Ok the controls on the front are a bit naff, they feel and look a bit cheap but I guess you can always replace them.

I did attempt to replace this with a Seymour Duncan powerstage 700 - sent it back, bought another GPA400 :)