...

Steve7 wrote: Bigger question is what's the difference between the diamond and the standard...

I liked the original Ultra-Linear, it was a nice "valvey" sound which worked well with most headphones. It was only after a minority publicly challenged me about hiss that I had to redesign it. I personally couldn't hear any hiss under normal conditions, and only after donning a highly sensitive pair of headphones and going into a sealed sound-proofed room could I just detect it. It turned out to be owners of IEMs who were doing the complaining, and I guess with an extra 20dB sensitivity it could be made out.

The DE version saw the UL module bandwidth reduced slightly to increase negative feedback which decreases noise (hiss). The headphone impedance sensing circuit (which the Hi-Fi Choice recommended SRGII also has) also had to go to get the noise even lower, and therefore the output stage was redesigned with a fixed low impedance output, which required beefier transistors to handle the increased short circuit current.

The sound between the models is otherwise similar.

...

Edited by Hbuus - 31 Jan 2016 at 3:35pm

I've a Solo UL and it works very well with the headphones I use, mainly Audeze LCD-2 and Sennheiser HD540 and 250. A lovely musical sound with great clarity.