Guitar lacking bite, vocal lacking presence

Did we time warp back to April 1st??!

Looking past the setup, you don’t identify your source. If there is an issue with the source, and/or it’s connections, even the best system can’t make it sound good. 

plus 1 ear cleaning and audiologist check-up

It appears that you are describing a lack of dynamic contrast.  This could be dynamic compression.  Or, phase cancellation (the room).  Or, both.

Right off hand, it looks like there may be a power strip with lots of stuff plugged into it.  You might try plugging the power amp directly into the wall to see if that helps.  The unknown source makes it difficult to zero in on the problem/remedy.

It could also be that everything is "okay", but the speakers lack the dynamic impact that you are looking for?  87 db efficiency isn’t "low", but there are high efficiency speakers out there that require 1/10th the power to drive that will push the guitars and vocals more out front, compared to the Thiels.

A good evaluation "tool" for room acoustics is to set the preamp  at a fairly low volume level and set very close to one of the speakers.  Does it sound better?

While this system may not make the cover of Stereophile based on its aesthetics, I’ve seen much worse.  We had an amp come in to the shop for repair recently, that when the cover was removed .... I’ll just say I’ve seen cleaner Porta Potties at outdoor music festivals. 

@andy2 ...+10 on getting your hearing checked.  For any and all who've been exposed to loud anything....concerts, drag races, weapons in conflict or sport, a pissed spouse....  Most hearing aid dealers will do it for free.

If you've suffered loss, Don't Scrimp On The Pair.  Joe Namath is embarrassing hawking the cheap seat set on the tube; you can do better using your cell phone with a decent set of buds.

Case in point, and I'll argue with one or all:
The pair in my ears cost more than all of my collected equipment, the eq of a new Mac Anything (although I could give a flip over what most likely cost)...

Anyone pushing 50+ should have been checked and done by now, and I could tease mercilessly those who claim otherwise...

BTB, I hope you've gotten your gear off the floor; just common floor dust isn't what you bought them for.  Get a stand of some sort, unless you need to touch your toes a lot....*teasing*  

A little cable control with some zipties will improve the 'look'...some will claim that having ac cords wound into the signal paths of your ic's and the speaker cables (nice fat ones, tho'..👍😎 ) isn't rational and may cause subtle interference that's easily ducked by separation.

Try to ditch the plug strip, and Yes, amp to the wall...

Drivers farther apart....a pair of my diy omnis' can give me a 'sound stage', but they're meant to be desktop drivers with a small sub....

Go forth an conquer...

Pardon my apparent crankyness.....I was woke up this AM by our 27# dog 'bunny-hopping' 6' onto our bed and landing on me...thought the wife had tripped and fell in some fashion (but the impact weight was wrong *L*).
Dog repeated the jump shortly, blew the landing, and got my elbow wacking his head as well....nil damage to him, but my right shoulder didn't appreciate it much...

"....abolish Monday mornings and Friday afternoons...."
(Dire Straits; Industrial Disease)

Cheer up, all above (except the aids) shouldn't cost more than you might spend on anything else this week....😏

Good variable factors, J