Comparisons between Pass Labs and Pass/Threshold

Can anyone offer listening comparisons between any of the new Pass Lab amplifiers and the older Pass-designed Threshold equipment? I presently own both the Pass/Threshold S300 and the S550e, the former purchased new and the latter purchased used/mint. Those are the two older Pass amps I know best. Do they have close counterparts in Pass Labs amps? Is it worth trading up? Those are the kinds of questions I am most interested in. Thanks much.
Yes, it's worth it!

I currently own a Threshold Ta-300. I have just finished auditioning an older Pass Aleph 0s. The speakers are Apogee Mini Grands and Vandersteen 4's, the TT a Kuzma and the preamps were Coda 04r and Melos SHA/Gold.

The Aleph is so much better than either my Threshold or a friends Coda 10 that it's not even in same league. I've been telling my hifi buddies that I really wanted to audition the Pass stuff for about the last year. I figured that it might be a bit better, but the difference relative to price might not be worth it - I was wrong!

Specifics - The Apogee's are a horrible load. We never figured that a 30 watt amplifier would drive them. We actually hooked it up as a bit of a joke.... The joke actually turned out to be on us! The soundstage grew to about double its normal depth and the speakers literally disappeared. Further, the sweet spot grew to the point where you could actually move around and stay in it (those that know the Apogees know that they are amazing but very finicky with placement and the sweet spot) We just sat there stunned and blown away that this little cube of an amp was that good....

Its sound characteristics are very close to a good tube amp. The image is laid back and very open. The amount of "air" around the various instruments is simply amazing. You hear everything going on in the room, actual finger plucks, the hammer hitting piano strings, etc. The interesting thing is it doesn't seem to have a sound of its own. Tube amps tend to have the "bloom" that changes based on which tubes you're running. This can be an advantage for system tuning but it can also be a double-edged sword because of tonal change. The Aleph just passed what was given to it with no changes (as should be the case).

Nelson is on to something with these newer designs. I've always been pleased with what I've heard in his equipment, but this later stuff is amazing and actually worth the $ IMHO!

Lastly, two things: First, the Aleph is no longer being built by Pass. I have yet to hear the new X-series but my assumption is it will be even better. This makes me sound biased, but the reality has been that the progression of his circuit designs have each sounded better. I have no reason to think that it wouldn't continue to be the case. Get an X series from your local dealer and bring it home to try it out. If you're blown away, buy it! We have to make sure that Pass Labs stays around...

Secondly, the downside of the minimal gain stage design is that you must have a preamp that can swing voltage. We ran the Aleph balanced with both the Coda and the Melos. Both were able to drive the system to volume levels that were plenty loud; but both were very high up the volume scales to do so....

Finally, prior to this audition, I was in the mindset to change over to tubes. The hassle has been finding decent tube amps capable of dealing with the Apogees. I'm no longer going that direction. The Aleph I heard was so much better than any other solid state amp I've heard, that the Pass stuff is my new direction. It gives me everything that I love about tubes with better base, more air, and no hassle. It's the best of both worlds IMHO.

For the record, I've had Krell, Threshold, Sumo, McCormick, PS Audio, Crown, and Coda in my system. Nothing else was anywhere near this little amp in performance. Its 30 watts single ended class A and it never ran out of steam during our listening sessions. The Krell KSA was 200 watts of class "A" and was dull and lifeless compared to this little Aleph! I don't know what Nelson has done, but he's on to something....

If you can afford it, I'd give his current stuff a try. I would guess that you will be blown away!

Disclaimer - I just finished spending a week with this little gem and now have to figure out exactly which model I'm going to buy. I also want to try the X-series and I'm trying to figure out if I can sell my dog to afford one... I am not a dealer or associated with Pass Labs in any way.

Good luck and have fun,

Those are great comments. The nearest Pass Labs dealer is a 3.5 hour drive (even with troopers snoozing), so auditioning is not routine. My associated equipment consists of B & W 801 Series II speakers, Threshold Fet 10 Preamp, and Sony SCD 777ES CD player. My continuing enjoyment of the latter has, for the time being, reduced use of the VPI Mark III TT with Audioquest PT6 and Blue Point special. I moved to the S550e from the S300. I have retained the S300 for alternate use or possible trading. I am a satisfied customer of Nelson Pass designs. Based on my experience, he is a dedicated designer and manufacturer of solid, high-quality equipment. The next Pass step, I suspect, would be to audition the X series.
steve,you mentioned the amp is 30 wpc.Are you sure you meant the O's and not the aleph-3?