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.
theo714
This might have already been covered, but do you have another source besides the turntable?  CD player or streamer to hookup to the Luxman 509x and check, if the same distortions are heard on same tracks?

that is what I would do before getting new speakers. 
Are you using the phonostage in your 509x?  If you are that is probably not so good match with a low output Koetsu. The loading of 100 ohms is probably not optimal for that cartridge. I know it was not for my Ortofon Cadenza Black. You probably need 400 ohm loading. 
That cartridge with is 5 ohm internal impedance is perfect for a trans impedance type phone stage such as a Sutherland Little Loco. That is what I currently use. It is amazing! 
You could always go the route of a step-up transformer and then go into the MM of the Luxman. I have used Bob’s devices in the past and they are awesome quality too. 
Jason
Post removed 
@millercarbon is a troll trying to push his ideas and equipment choices on everyone else. If that doesn’t work he’ll bully you. He doesn't have a life but has plenty of money if you believe what he says. He spends his time posting on Agone, whatch his posting numbers, they go up a couple hundred to thousands every week.
I hear zero distortion of DK’s look of love album. I’ve both the 180 gram lp and a 33lp. Also I have the cd. I use electrostats, which are very revealing! All of these have playback of this album with zero distortion. Something is wrong in your system. 
$10-$15k is enough money to get anything you want and the good thing about buying used is you can resell if they don't workout. I usually just tell people to go up the line in the same brand they already have since thats the sound that will probably sound most natural to you.