I will offer a somewhat differing view. I agree with the above comments that the hybrids marked a downturn in ARC products-- at least to the qualities I listen for. I have worked on most of their gear up to the mid-1990s. The best amp they ever made, IMHO, was the M-100 and the best preamp being the SP-10 (although keeping 12 quiet tubes in it was a challenge). However, do not assume that the 70s vintage stuff is over the hill. Updating the coupling caps, some resisitors and the feedback caps will give you an amp, or preamp, that is highly competitive. If you are technically inclined, some work on the power supply will then give you an amp or preamp that is as good as you can buy. The output transformers of the 70s tube amps are excellent quality.
