All I can say is that I have an MP-501 V5 (the latest version) and it is a very fine, and very affordable piece of kit. I bought it having had a very good experience over a year or so with the smaller MP-301. There is a dramatic improvement and, assuming the 501 lasts, I expect to keep it for many years. As it is so inexpensive it would not be a tragedy if it did't last, but it seems well-built and in the course of 5 versions, the designers have clearly improved it.
Like the PrimaLuna the 501 is also auto-biasing.
I am not sure that you need be concerned about the points your raise at the end of your post. For decades valve/tube amplifiers have not had these features and, when the tubes fail, all is well after replacement. I'd suggest that of all the things you need to consider when making a purchase, your concerns need not be amongst them.
The 501 uses KT120 power tubes which are current production and should last a long time. It uses readily available and very cheap driver tubes. I have bought lots of various types for very little on eBay and have enough to last me out now!
I listening to the 501 now and am enjoying a fabulously detailed, rich, three-dimensional impression of the Vienna Philharmonic playing Brahms. It may not matter to you but the 501 looks beautiful too.
A lot depends on your budget. I took the decision to go for the (cheaper) 501 and buy the very best DAC I could afford (Chord Qutest). This strategy worked for me.
Hope this helps.
Like the PrimaLuna the 501 is also auto-biasing.
I am not sure that you need be concerned about the points your raise at the end of your post. For decades valve/tube amplifiers have not had these features and, when the tubes fail, all is well after replacement. I'd suggest that of all the things you need to consider when making a purchase, your concerns need not be amongst them.
The 501 uses KT120 power tubes which are current production and should last a long time. It uses readily available and very cheap driver tubes. I have bought lots of various types for very little on eBay and have enough to last me out now!
I listening to the 501 now and am enjoying a fabulously detailed, rich, three-dimensional impression of the Vienna Philharmonic playing Brahms. It may not matter to you but the 501 looks beautiful too.
A lot depends on your budget. I took the decision to go for the (cheaper) 501 and buy the very best DAC I could afford (Chord Qutest). This strategy worked for me.
Hope this helps.