plinius sa100III v pass x150

What is the rest of your system?
Because both components can sound not-so-good if not matched well with a given system.

KF

Jrud- Just a word of caution. Listen before you buy!!!! OK, actually, a few words. Reviews are at best a positive when it comes to resell an item, but they mean very little in terms of your potential enjoyment. If possible, I'd suggest considering a new amp that would have a money back offer, possibly a PS Audio or some other manufacturer with a similar offer? Most used gear isn't available with an audition clause as part of the sale. Just curious, but have you considered a good tube amp instead?:-)
Good luck.

If you are buying used and have the funds, buy both and compare in your own home ... sell the one you like less. Best of both worlds, used pricing and an unlimited home audition.

The Plinius has good input impedance and input voltage sensitivity. The manual doesn't mention the db gain, you should ask plinius what it is. I think the Pass would be harder to integrate into a system due to its relatively low input impedence, but it depends on what preamp you going to use. Pass Labs website doesn't mention their input voltage sensitivity, you might want to ask them.

Unless you are prepared to buy used and sell the loser proceed with caution. You should really listen to both before you buy if you are going to buy new. Galen Carol Audio carries both lines. You might want to call him and ask his opinion. Maybe you could arrange an audition or fly to San Antonio to visit his showroom. Don't laugh at the idea, Galen gives good discounts and no sales tax unless you live in Texas.