Ran my 2.3s with a 4b-st for many years, and liked it plenty. Low end was nice, good authority, but I wouldn't say the last word in definition. Originally had a VTL TL2.5 (tubed) in front of the Bryston, the switched to a Rogue 99 Magnum (tubed), and then a Plinius CD-LAD (solid state). The progression of low end defition from the start to the end of that upgrade path was among the most notable differences -- most notable with the switch to the Plinius, which made the low end much much more precise, defined and weighty. Through all of these upgrades, however, I stuck with the Bryston.
Throughout the same process, I switched from a AH!Tjoeb 99 to a Meridian 508.24, which was also a huge improvement in terms of definition (and not just low end, but throughout).
These days, I've bridged the Bryston and it's been relegated to running the center channel (ok, gross overkill, I know) -- and I'm running the 2.3s with Rowland gear (monos and preamp). That was another huge difference -- with the precision, definition and micro-dynamics almost disconcertingly improved. Clearly, I've been drifting from a largely tubed setup to all solid-state. Definition and low end authority has been vastly improved in the process. But not without costs. Thiels have been accused of being somewhat clinical, and I originally put a lot of tubes on them to address that, but as I've run them with lots of different gear I've become more convinced that the speakers are remarkeably neutral and thus broadcast the character of the gear you drive them surprisingly effectively. As far as solid state goes, Meridian and Rowland are perhaps warmer than many (if not most), but tubes they aint.... Suits my tastes just fine, but, hey, the ears you aim to please are your own.
Ok, rambling aside, the Thiels can be a bitch of a load and respond really well to more power. 100wpc into 8 ohms (the Thiels I think average closer to 4) is probably a little anemic for their sweet spot. Hate to sound reflexive in simply proclaiming that throwing more power at it will cure your ills, but I think you'll find a great improvement with more quality power. As for Bryston v. Aragon, no personal experience with the Aragon, but the Bryston is a great amp (and an amazing company, best warranty in the business is no joke) that would certainly suit your needs and likely be a real improvement in the departments you're looking for. (Though, I would note, I believe Aragon is out of business (is that right?) -- so, between the two -- I'd lean towards the backing of Bryston, all else being equal). Best of luck and enjoy.
Throughout the same process, I switched from a AH!Tjoeb 99 to a Meridian 508.24, which was also a huge improvement in terms of definition (and not just low end, but throughout).
These days, I've bridged the Bryston and it's been relegated to running the center channel (ok, gross overkill, I know) -- and I'm running the 2.3s with Rowland gear (monos and preamp). That was another huge difference -- with the precision, definition and micro-dynamics almost disconcertingly improved. Clearly, I've been drifting from a largely tubed setup to all solid-state. Definition and low end authority has been vastly improved in the process. But not without costs. Thiels have been accused of being somewhat clinical, and I originally put a lot of tubes on them to address that, but as I've run them with lots of different gear I've become more convinced that the speakers are remarkeably neutral and thus broadcast the character of the gear you drive them surprisingly effectively. As far as solid state goes, Meridian and Rowland are perhaps warmer than many (if not most), but tubes they aint.... Suits my tastes just fine, but, hey, the ears you aim to please are your own.
Ok, rambling aside, the Thiels can be a bitch of a load and respond really well to more power. 100wpc into 8 ohms (the Thiels I think average closer to 4) is probably a little anemic for their sweet spot. Hate to sound reflexive in simply proclaiming that throwing more power at it will cure your ills, but I think you'll find a great improvement with more quality power. As for Bryston v. Aragon, no personal experience with the Aragon, but the Bryston is a great amp (and an amazing company, best warranty in the business is no joke) that would certainly suit your needs and likely be a real improvement in the departments you're looking for. (Though, I would note, I believe Aragon is out of business (is that right?) -- so, between the two -- I'd lean towards the backing of Bryston, all else being equal). Best of luck and enjoy.