That's a great question but are you talking control room or mastering room? Or all three?
An amp that goes from Control room to Mastering system to a home playback. Some folks are going to say Bryston, some are going to say Crown and a few old schoolers might even throw in Crest or Yamaha. I have my favs.
But to ask this question consider the 3 different types of speakers in the same settings as above. If your taking JBL to all three places that's a big difference than lets say B&W. I think the answer would really depend on your specialty as an engineer. I've built and owned studios that had all 3 room types and system types (I used MGA speakers as well a mix of others), but I have a feeling most here are going to try to lean toward their home audio senses instead of thinking the 3 different areas of purpose.
mg