ARC tube amps have a definite warm “Tube house sound. And while I don’t currently have anything, I can assure you they make great products. Having said that, the sound isn’t for everyone and or every speaker.
Also, depending on your listening levels and whether you use sub’s, 100 watts might not be enough power for the 3.7i’s. (They really like current) but If you use an active crossover and roll the Maggie’s off @65 htz,, 100 watts is way more power than you need. There are a bunch of other variables you will need to consider also. Room size and and acoustics to name a couple.
Have you ever considered getting a hybrid amplifier? Tubes on the input section and Mosfets for the output stage?
All the best.