I have a couple of points to add.
1) Your Benchmark is one of the best amps ever made and has received rave reviews across the board. It's going to be hard to beat.
2) If you have the itch to experiment with amps I would suggest buying a used tube amp so that you have the chance of getting something that sounds more different. Your Golden Ear's are suitable for tubes (they have good sensitivity and a fairly flat impedance curve).
If you buy a used tube amp you can keep it as long as you want and if it's doesn't spew fairy dust out of your speakers you can sell it for about what you paid for it.