Even though there have been a couple previous reviews of this amp already, I thought I'd post some of my impressions.
I had been using another one of Ray's amps, the Protector, with the TAG balanced cable attached to my JH Audio 16 pro custom monitors. I was able to compare the Protector to the prototype SR-71B at the last Chicago meet. RSA house sound for sure, but the SR-71B is warmer in the midrange and has a feeling of more power & drive.
Couple months later I had my very own SR-71B and I am very happy with it.
Build quality is top shelf as usual, but we all knew that didn't we?
Even as most of Ray's new amps seem to keep shrinking (I think they will be implantable soon) I actually appreciated the larger size of this one. It's about the same width as an iPod Classic and only a little shorter. That makes it easier for me to stack one on top of the other & carry them around. I also like the longer volume knob which is easier for me to get hold of with my fat fingers.
I made up a cable to come from the balanced outputs of my Modwright modded Logitech Transporter to the special 4 pin balanced connector that is required for a fully balanced signal.
Is there a difference between a balanced input & single ended?
Yes, there is a wider soundstage and a sense of "ease & clarity" that is missing with a single ended input. Not night & day different but if you have the option on your source it's well worth doing.
So far so good, but can it drive the big cans?
Replaced the 1/4" plug on a stock Sennheiser cable with the 4 pin plug so that I could use the balanced output on the SR-71B to power my HD-650's. These headphones I've had since they came out and have been the longest lasting component in my system. The balanced outputs fed the SR-71B while the single ended outputs of the Transporter fed the Bottlehead Crack amp (With Speedball update).
The Crack has been one of the best amps I've owned to drive the 650's. Could the SR-71B keep up?
Yes & then some. It's almost the equal of the Crack!
With the 650's the SR-71B is quieter than the Crack as you might expect and sounds very clean & detailed. I was also pleasantly surprised that the SR-71B drives the 650's almost as well as the Crack. It does not quite have the "richness & tube sound" of the Crack but it comes very close. In fact, you'd never notice the difference if you weren't comparing them side by side.
This might be the only amp you'll ever need.