Model TL-R1. I've now used them with three different speakers (Harbeths, Spendors, and Pinnacles) and they simply add a delightful extension of high frequency air and harmonics. Absolutely no glare, etch, harshness, etc. They do what the man from Merlin says his speakers do - help "light up a room" and only in a good way. Sometimes I'll shut them off (most often late at night) when in the mood for a more burnished, darker tone. But they get turned back on soon, at least by the next morning. Kind of like having two amps or different sets of tubes to swap.
I have to say this again as it can't be stressed too much - there is absolutely no tension, etch, tizz, harshness, hardness, glare, distortion or anything like that caused by the Tonians. They are actually on the slightly sweet side of neutral and seem to my ears to be voiced as properly as possible. If number 1 is hard, glarey, and etched, and 100 is soft, plump, and dark (and 50 is dead neutral), the Tonians are 52. I think this is a brilliant design choice but then I'm deadly allergic to any kind of glare, etch, hardness, or tizz. They make drum sets sound awesome. I just love listening to Art Blakey music with the Tonians in line.
Did I mention they also open up and illuminate the soundstage in a musical and interesting way? Some speakers do it by hyper-detailing the presentation, the Tonians do it by releasing high frequency musical sounds that help put the musicians (and recording venue) right in front of you.