NHT 2.9 vs. Thiel 1.5 (or other?)

Hi, I own a pair of NHT 1.5. I am looking to upgrade to a more full-range pair of speakers and still to have some room left for me in the apartment after that. The electronics I use is a Sony 333(?) ES receiver and it's 24/96 built-in dac which I find superior to the DAC in my CD player Sony CDP9 ES. I listen mostly to acoustical instrumental/vocal music (classical, jazz, alternative and the like). My room is approx. 14 by 26 (with dining area in it, so effectively 14x20) and I can only position the speakers along the long side of it. Could give them up to 2-3 feet from the back/side walls. I recently auditioned the Thiel .5 and 1.5 side by side with Vienna Acoustics Bach and Magies 1.6. To my liking the Thiel 1.5 gave me most satisfaction (Vienna had boomy base, Magies had somewhat less precise high end and very narrow height of the sweet spot and also very low efficiency plus the bipolarity may be a problem). The NHT 2.9 has supposedly lower low-end (29 Hz) compared to the Thiels (42 Hz). The problem I have with my NHT 1.5s is that, even though they are exceptionally clear and accurate, they sound fatiguing to me and I suspect the larger 2.9s may be similar. I understand that this may be due to the electronics I have, but that’s the $$ situation right now. Can anyone provide advice primarily on the choice between NHT 2.9 and Thiel 1.5? Other suggestions will be appreciated too but should not exceed $1500. Thanks, Mihail