I have owned B&K 140 and EX442. I also own MMG. Do yourself a great big favor. Replace the B&K at the same time. I think the B&K amps are the single most over-rated products in the audio world. I have, over the years, accumulated a pair of Classe DR9 amps, bridged to mono, into first MMG and now 1.6QR. A single DR9 or Krell KSA80B (my rear channel amp on the MMG's since receiving the 1.6QR) will perform magic. If I had to choose between 1.6QR on a B&K or MMG on a Classe DR9, I'd take the latter in a heartbeat. Dual DR9 mono into 1.6QR has the system to the point where I don't think I can confidently improve it without risking degradation. What I haven't preached about yet is the preamp. It is the most important component, in my book. Get a good preamp. Everything in my system except MMG were purchased used. I have $30k (new) that I paid $6K. I have the best $6k system I can imagine. Sam Tellig was on my s**t list for years because of his (in my opinion) mis-guided raves about B&K. Because you can buy used, you can do much, much better.
B&K and Magneplanar MMG?
Has anyone attempted matching a B&K ST-140 with the MMG? At 105W/ch, the B&K is stable into 8 ohms, but I don't know how it would react to a 4 ohm load. My trusty B&K has been a workhorse for many years, and I wish to keep it in my system. My speakers, however, need replacement and I'm intrigued with the offer from Magnepan for the MMGs.