I just stepped in to this sound system area. I purchased Bowers & Wilkins CM1 and looking to purchase suitable integrated amplifier. My music source would be spotify from my cell or iMac, connected through airplay express to digital input to one of those amplifiers My options, Rotel RA-12 Marantz PM7005 YAMAHA AS701 After lots of research, Rotel usually suits the best with CM1, Marantz does a descent job and Yamaha amps might be the last resort among three producers here. However, I still wanted to hear more opinions about how they go along with CM1. Price-wise, I think I am going for used ones... and can get them $550, $750, $550 respectively. What would be the best possible choice among three? and any recommendations for bluetooth device? Also, I was looking at tube amplifiers... specifically, YAQIN M84L ($500) or YAQIN MC-13S ($700) but I have to purchase separate DAC for those amplifiers... There were not much information that I could find about tube amplifiers which matches with CM1. What are your opinions?