Which preamp for a pass labs?

I ran an LS25 MK1 into an X350 and thought they went together really well. I now use a Ref2 with the X350 and again a good combo. It's like McGrogan said, they complement each other very well.

The LS25 is now running an ARC VT100 and the sound is much leaner than it was with the X350. I'm still trying to work that out. It could just be the VT100 is just getting tired. I bought it used.

I will admit I've never tried any of the Pass preamps. It probably wouldn't be a bad choice. The LS25 does have an incredible amount of input/output options so that might also count for something.

Actually at this level these components are balance from input to output. There is no balanced to single conversion going on. Both the LS25 and the Pass X amps are meant to be run balanced but will work with a single ended connection. But that's really kind of a waste of what these components can do. If you run the LS25 single ended you're literally only running one half of the preamp.

If you're going this route go buy good XLR cables even for short runs. I agree a lot of components are single ended internally but not the ARCLS25 or Pass amps. Otherwise you'd be better served with components that are meant to be used single ended. It's part of the reason these boxes cost what they cost.