The guy at Pass labs said it just like the people I have talked to. the 150.5 is much better than the original 150 and more on par with the upper level .5 amps. I found mine just looking one day and thought I better jump at it while this lasted. the price I got mine at was a steal compared to new and almost too good to be true. I must say though that the 150.5 does not seem to come up for sale very often. The prices you mentioned for the 250 seems very good though and I would not hesitate at all if the amp checks out as been taken care of. Unless a person has severe upgraditus or just have a whole in there wallet bigger than most I would say most audiophiles would be happy ending their journey at the Pass .5 series amps. I know I have never heard an amp in my life that gives music this kind of life and energy while keeping all the detail and dynamic slam. I recently added my XLR connectors back into the chain between the preamp and amp and also changed the interconnects between my dac and preamp. made much difference and now I know why people say to use the balanced connectors on Pass amps. It really opened up the sound and let the detail and lifelike realism flow. I really noticed it with the dynamics of the music between soft and loud passages.