First Sound preamps....feedback please.

FYI. Make sure the FS's output is compatible with your amp. I wanted to audition one, but it's power output was too low to be very effective with my amp.

All preamps output different voltages. Ask your amp manufacturer (or check your manual) to see if they specify certain maximum/minimum input voltages to work ideally with your amp. There could be an issue if your amp's input sensitivity is low and the preamp outputs low voltage. You will probably be able to listen to music at lower levels, but may not be able to take advantage of your amps power and listen at loud levels. You could turn the volume all the way up and it wouldn't be as loud as you'd like. The opposite is true too...a sensitive amp and high voltage outputs on a preamp could mean that you'll never be able to turn your volume control past the 9 O'clock point. It all comes down to listening preferences and convenience. If I remember correctly, the First Sound's output is on the low side. They would probably mate well with most amps, but my amp happens to be a low sensitivity design and the output of the First Sound was lower than my amp manufacturer's recommended input voltage. It may not be an issue for you at all, but I figured I'd mention it...just in case. That said...I was dying to audition one. They appear to be great tube preamps.