The JC1's are a top choice for those that drive Soundlab speakers. I believe the load is similar between the Soundlabs and the Innersounds. You have a beautiful set of speakers, as one member wrote "you probably will love both". It's tough to suggest one is much better than the other when your surroundings, source, connects, etc play such a big role in the sound. Then of course, there is your taste in sound. Unless you are able to set them both up and A/B them, you may just have to pick the best deal and try them.
It seems they are both around the $3500 range used so that is a wash. There is something to be said for monoblocks from a beauty and balance standpoint. The truth is that there are multiple threads regarding both amps are excellent. Both are able to drive a large range in ohm loads. Both have tons of power. Both have excellent build quality. I believe the Halo's are more pleasing to the eye but that is a small point and a personal preference.
If you know of someone local who has one or the other and would allow you to trial it for a day or two you could always purchase one and borrow one if your really wanted to do a side by side testing in your environment.
The great news is that both amps are hot on the used market right now and don't last very long but there are enough of them out there that they come up almost every month. If you have the coin, buy both. Audition them for a week or so, then sell the one you like less! :-)
I am in a similar situation with my Soundlab A-1's. I am refinishing a set right now and need to make a decision on amplification in the next 6 months. The JC-1's are on my short list. I also respect what Dr. Sander's has done with his innersound/sander's sound amps. I am actually suprised his amps were bright on your speakers but it may have been your environment, related equipment or taste (and that's just fine, no offense intended). The spectron equipment rounds out the short list for equipment. The running temp. is definitely a bonus, especially if you have a smaller room, or one that is tight and doesn't have much air movement. In an hour or two you can really bring the ambient temp up.
Good luck with you quest. It's half the fun. You have a couple of great amps to choose from. FWIW, buy both, try them and sell the other. You can't go wrong. Then you can let us know which is best in your setup. I would be interested in your findings.
Good listening.
