Just wanted to chime in here....but first of all thanks to Miguel for graciously loaning me his Solo SRG! I was surprised on how small the footprint of this amp is, much much smaller than the Extreme.
Source: Headamp Pico DAC and ALO Wooden V-Cap Dock (both playing lossless files)
Cans: Grado HF-1 with Bowls
Cables: DIY Jena RCA-RCA and BJC Mini-RCA
My early impressions:
Treble - definitely well defined and extended, reaching high notes without any difficulty. I did feel thought that with certain tracks, I felt a little bit of brightness which may be chalked up to system synergy or just flat out crappy recordings. Not prominent enough to bother me a lot but still there. However, I do admire the great treble extension that this amp has, I wish my Extreme could borrow some of it!
Midrange - Nice with a slight "warmth" to it. Not as lush as a tube amp but still excellent mids. Female vocals have just the right amount of weight without much coloration at all. Not as romantic as my tube amp which may actually be a pro to some people.
Mid-Bass - This is the area I feel the SRG excels most at. First thing I said about this amp was "Wow this amp has great bass weight and most importantly control!". I later realized that I was actually referring to mid-bass and not bass/low bass. Bassy string instruments sound superb with this amp.
Bass - Good quality, not flabby or boomy. However, I think I would like just a tiny but more quantity and lower extension. If Graham can find a way to wring out 1 dB around 60 hertz, that would truly help here. As you see, this shortcoming is a very small one, any more than 1dB I think might be too much. On a positive note, I wanted to add that while it could use more bass, it presents whatever bass it has in an excellent manner; it doesn't sound like it's trying too hard.
Overall Impressions - Let me start by stating that I prefer tube amps. In fact, I've never owned a full-sized SS amp though I've tried a few different ones at meets.
The SRG has a slightly forward character while the Extreme has a more laid-back but sweeter/more euphonic presentation. However, as I have stated earlier, the Extreme can use a little bit of the extension that the SRG has.
Will this amp convince me to switch to SS? Unfortunately not. However, no SS amp has convinced me to do so anyway. I can't really see myself totally abandoning tubes but I can see myself owning a SS amp to complement my tube amp. But if I really had to go SS under $1000, I would put this amp in my shortlist together with the TTVJ FET-A. I tried the FET-A at a meet and liked it's sound signature enough to want to try it again; as a matter of fact, I signed up for the loaner program.
I would also not hesitate to suggest this amp to someone who is looking for a mid-priced SS amp. If I had to guess, I think that this amp would synergize well with laid-back and bassy headphones like the HD650, D5000, etc.
Again, thanks to Miguel for loaning me this amp; I am enjoying it as we speak