OK, maybe this is a bit premature since these amps just came out I couln't resist pulling mine apart and having a look. Construction is very nice-pretty much on par with boutique stuff built in the US. The only thing I saw right off that I'd want to change would be to upgrade the coupling caps. I'm a vintage Jensen guy so I installed a nicely broken-in Weber Sig10AS. I've tried a few higher-power ceramic Emis in other amps and always went right back to the Weber Sigs. In this case I much prefer the stock speaker. It's pretty even in the mids, plenty of highs and the bass is well suppported. Considering how loud the amp is it's probably fairly efficient. I'm not even tempted to try to upgrade it. I was getting a lot of rf interference so I thought I'd open it up and check to see if it had a grid stopper resistor on the input. It didn't so I added a 68k. It worked-the amp is no longer a radio For coupling caps the amp has .047s in the preamp and .1s in the power amp. I'm hearing a little more low mids than I like so when I upgrade the caps (to Mojo Dijons) I'll go with .02s in the preamp. For filters it has 22ufs in the preamp and 47s in the power amp. I'll drop the filters in the preamp to 10uf to loosen it up. It's a fairly quiet amp but there is some hum even with nothing plugged in. It's not bad at all but I did notice that the preamp and power amp are grounded together. The next time I open it up I'll try grounding the preamp and power amp separately to see if it quiets it down any. Did this to a 5E3 I built and it made a huge difference. All said, this is an amp that doesn't need mods to sound great, which is really amazing considering the price. VHT is going to sell a ton of these things.