Older PURE CLASS-A Amplifiers


I am looking at some older Pure Class A amps and am curious as to are they as good as some newer amps like the Pass X150, and which ones are recommended, and have they been compared to each other anywhere? Thanks much for the recommendations.

I am considering the following PURE CLASS A amps:
Threshold T-50
Monarchy Audio SM-100 Monos
Monarchy Audio SM-70
Forte Model 4
tpk123
nobody's mentioned the Pass Aleph series amps, amongst the most famous of all class a solid state amps...are they not considered to be in the same league as the above mentioned amplifiers??
The Aleph-3 is the best amp I have ever owned.
Too bad I bought some Thiels and had to go to a bigger amp.I wish I would kept the amp and bought different speakers (for power only as I love my Thiels) Although this thread asks for CLASS A bias amps only.I would like to add,my Threshold A/B S/300 is a killer amp!
It drives my Thiels with ease,and then some.
The Platinum Reference I is the biggest chanllenge to power amps. I have yet to find anything that make it sound acceptable to my ears.
I have matched it with about a dozen amps 5 years ago (from $$$$ SS amps to tube amps )and gave up at the end. No matter what you feed through it, it never sound as open and relax as some other better monitor speakers. I ended up ATC SCM10s as it sound much more realistic, relax and open ( very dynamic without the constrain I felt from the Platinums.)
What is your experience of intensive wear that pure Class A designs impose to output transistors? Does Class A amps were at a faster rate than a/AB?, which are the sonic implications of such "wear" in older Class A designs?
The older Threshold S and SA series amps can still hold their own against the newer equipment. I am quite familiar with them and have heard many of them over the years at a local dealer that used to sell Threshold. I currently have the S350e Class A/AB model. As someone else had mentioned, I think I would shy away from the T-50 model because I also have heard that the IGBT ouput devices used by the T series are no longer available. All of the older Threshold amps that I have heard, including my own have delivered a relatively neutral presentation, depending on what other components were also in the chain. IMO they have a similar sound to the Pass X series amps. If you happen to see one of the class A SA series for sale GRAB IT!