I, along with two friends, compared the ML 334 to the Plinius SA-100, a Bryston 4B and a Coda 10.5 using the same system: B&W 802 speakers, TARA Lab Gen II interconnects and a Resolution Audio CD50 player - no preamp. It was unanimous, we all preferred the ML 334. Great transparency without being shrill or harsh on top with a rich midrange, terrific bass and a large and realistic soundstage.
We've heard the Pass Labs, but at a dealer on a different setup with Revel speakers. We did not like the Pass X350 as much as the Levinson 335 (the 335 has 250 watts, the 334 has 125 watts). The Pass had a good midrange and good bass but seemed to have a harsher top end (on the Revels) and a smaller, less specific soundstage.
As far as the ML 331, I've not had an opportunity to listen to it. I have heard, however, that the current series 334 is far superior to the 331. It could very well be that had we used a 331 instead of the 334 in our comparisons that we would have come to a different conclusion. My advise to you is try to compare them yourself, for your amp it's you preference that counts.
We've heard the Pass Labs, but at a dealer on a different setup with Revel speakers. We did not like the Pass X350 as much as the Levinson 335 (the 335 has 250 watts, the 334 has 125 watts). The Pass had a good midrange and good bass but seemed to have a harsher top end (on the Revels) and a smaller, less specific soundstage.
As far as the ML 331, I've not had an opportunity to listen to it. I have heard, however, that the current series 334 is far superior to the 331. It could very well be that had we used a 331 instead of the 334 in our comparisons that we would have come to a different conclusion. My advise to you is try to compare them yourself, for your amp it's you preference that counts.