This is good to know! I've just won a Sunn PB-10 Beta preamplifier on ebay to play my guitars through. The only noticable differences from the exterior is that the PL-20 has reverb and says PL-20 on it instead of PB-10.
I grabbed it because it was at such a low price including shipping to England and also I knew how rare the two Sunn rack units are, I'd never heard of either.
Josh Homme of Kyuss and Queens of the Stone Age fame played through bass amps, and he's one of my favourite guitarists of all time. So I'm really looking forward to playing detuned through the PB-10.
Just one question though: is there less gain available with the PB-10 compared to the PL-20? I hope they didn't cut the gain down for the bass version.
Thanks.
jM