I'm also using a pair of Apogee Studio Grands. They are really a great pair of speakers. The good news is that the Studio Grand ribbons are a pretty benign load. They come in around 6 mostly resistive ohms with little variation across the audible spectrum. They are very different from the early Apogee models such as the Full Range or Scintilla with 1 ohm impedances.
That gives you a wide choice of amps to drive them with. I'm using a pair of Pass Aleph 1.2s which sound great on the panels, but definitely violate your low heat requirement. You might consider some of the Pass X series - they sound pretty good and run pretty cool. Even tubes should work if you're so inclined.
That gives you a wide choice of amps to drive them with. I'm using a pair of Pass Aleph 1.2s which sound great on the panels, but definitely violate your low heat requirement. You might consider some of the Pass X series - they sound pretty good and run pretty cool. Even tubes should work if you're so inclined.