I had been happy with LM 508 for last 4 years.
Please note that I am using LM 508 to drive Main towers of Scaena 3.2 from 290 hz up using active crossover in above video.
I used to use LM 508 to drive Lanscne 4.1 or Altec A7.
I also consider upgrading to LM-523PA since latter use tube rectification with mono configuration for better focus.
If you do, please let me know your impression.
best
Thomas