Looking for new speakers

I'm looking to upgrade my Thiel CS3.6s -- I never thought I'd say this, but I think they are not good enough for the rest of my system. 

Within the last two years, I've upgraded my amplification to a Luxman L-509x integrated amp, and upgraded my turntable to a Luxman 171a. Overall my system sounds pretty good --- MUCH better than before the upgrade. However, there are some recordings on which there is definite distortion, particularly especially well-mastered 45s. For example, Diana Krall's Look of Love has so much distortion it's almost unlistenable. Even in the 33s, I can now hear a low-level distortion.

My theory is that when the Thiels were manufactured, the electronics were not quite as good as they are now, and definitely the recordings were not mastered as expertly, so these weaknesses did not show up. They were great speakers in their day, but, alas, I think maybe that day has passed, at least in my system.

I'm looking for something in the $10K - $15K range. Not sure if there's anything in that range that would be enough of an improvement, but I'd love some suggestions. It's been many years since I've looked at speakers, so I'm not really up on what's available at that price point.
Glad I'm not the only one to find it irritating when someone lays down the law (with conceit I might add) like it's the final word, each. and. every. time. Good grief, there isn't one opinion and everything else beneath it. 
Before you blame your speakers check if you have same issue with digital recordings i.e. CD player. If not could be you turntable. If same distortion is apparent with digital source,  try changing your interconnects and speaker cables. If the problem is still present, borrow a pair of speakers from your audio dealer or friend and see if the issue is resolved.  I doubt its the speakers.

Perhaps the Thiels are amp-sensitive.  I home-demoed the Thiel 3.5's with a 200 WPC Perreaux Mosfet amp and preamp. Mosfets are generally mellow, but the combo was ear-bleedingly bright.  I think the 3.6 was smoother, but once bitten...
My opinion is that you need to be more thoughtful about what is happening in your system before putting the blame on your Thiel's. One thing is true: the Thiel are very revealing and they will voice whatever is coming to them. Let me share a recent experience I had that may be helpful.
I have had a pair of Thiel CS3.6's since about 2000, driving them until a few weeks ago with Manley Labs Ref 250 mono blocks, ARC Ref2 MKII pre, ARC PH3SE Phono stage, ARC CD3, VPI HW-19 Mk4, Linn LP12, Benz Ruby 2, Van Der Hul One, and Transparent Ref cables. I was happy for a long time with my collection of what I thought were quality CDs and LPs. A month ago, my system changed to Pass Labs X260.8's (new, not broken in), ARC Ref 5SE (used), ARC Ref 2SE (used), Ruby LPS, Lyra Atlas, and Cardas Clear Rev.1 cables (new). The Thiel's stayed. For the first several days, I did not like it. There was all kinds of distortion, dullness, very disappointing. After 3 weeks of playing, everything changed, but actually two things happened. On one hand, many of my recordings sounded wonderful, hugely better than before. On the other hand and to my disappointment, I discovered that some of my "audiophile" recordings are not as good as I thought. My new system is revealing the truth.

In your case, I would suggest that you investigate the issue more methodically. For instance, play a recording that you are satisfied with, and from your collection, play another recording with similar content that shows distortion. Can you isolate the problem to the type of music of frequency band, i.e., vocals, instrument highs, midrange, bass etc.?
It may be that your Thiel's need to be serviced, but something else may be the problem. I would not assume that your new components are fine. Are all your components broken in?
Finally, I don't believe the idea that when the 3.6's were designed the electronics were inferior and so the 3.6's are inferior.

Lucky for me, I have finally located a pair of Thiel CS3.7's that I will be receiving this coming week, and my 3.6's will need a new home.