Amp upgrade, speaker cables or both

I've used various Tannoys over the years. I've found they all scale significantly with amplification - both quality AND power - though I must qualify this by stating that I listen loud. I'm not a 75dB listener. 

I've got a A23 (not currently in use) that I've tried on my Glenair 10's. It's serviceable, but really holds them back IMO. An A21+ should be a significant improvement (owned A21 in the past but didn't try with Tannoys). As a cheaper option, the NAD M22 (v1 or v2) absolutely clobbered the A23. The NAD class D has a slightly "dry" midrange so I think it pairs much better with a tube preamp. But the slam, dynamics, and clarity of this amp is such a fun ride on good Tannoys. The newer NAD M23 Eigentakt looks interesting! 

Anyways, I'd definitely do amp first in your shoes, and allocate most funds there. I've never regretted a splurge on amps. Cables have been more of a preference / random synergy thing, though with a long SC run I think you'll definitely here a difference. In one of my Tannoy setups I use a long XLR IC run, keeping SC's cables normal length, and it works great. 

Hello lloyd 1969!  The "in the room" difference in anticipated loudness is very poorly understood. Watch the VU meters on some piece of gear as some favorite music plays. Big jumps are common in Classical music, but much commercial music has a pretty steady volume. You have an amp with a 165 WPC rating. Somebody says you need 250 WPC. What is the real difference?  If you double the output power you get a 3db inctrease in room loudness. That is about the smallest increase the untained ear can detect. Of course, we audiophiles have "trained" ears.

So a 10 db increase in loudness requires a ten fold increase in amplifier power. (4x power is 6db louder, 8x power is 9 db louder . . .) So the jump between an amp cruising along at 1/10 th of a watt, gets a volume jump of 10 db from a cymbal crash and puts out one watt. if the amp had been cruising at 1 watt, the crash would require 10 watts. Can you see where this is going? Suppose you have very inefficient speakers and you're cruising along at 10 watts; the cymbal crash now requires 100 watts!  Suppose you had a 20 db jump in program mateiral - the choir jumps in as the bass drum thunders, you will need 100 times the amp power to handle the 20db jump in volume. In the case of the ten watt cruiser, you suddenly need 1,000 watts!  The little 9 wpc, 300B amp, rated as 9 wpc at 10% harmonic distortion must put out 10 watts to handle the 20db volume increase, and it can't. OOOPS!  Can you see why big amps are so popular?  The big amp sounds cleaner because it distorts less when pushed beyond its limits. In your case 165 watts verses 250 watts is hardly an audible difference. A 3 db loudness difference would requre 330 watts.) VERY few people listen with their amps cruising at ten watts. Maybe Dodger Stadium, but not you house or my house. So don't worry about amp power unless you want to go to at least 400 watts per channel. You want an amp that NEVER overloads when you are listening to your music at the loudest level you would ever want (unless the baby pushes the remoter control button, vaporizing your tweeters). Try better cables. Nobodys system is exactly like yours so you have to try aout a few cables to see if they are better than what you have. Remember, a 4 ohm speaker requires much more current than a 16 ohm speaker (common in the old days). That's why the old timers say cables don't make a difference. Their 16 ohm speakers didn't need heavy duty speaker wire because their speakers didn't draw much current. But lighter weight voice coils allow the speaker to move faster (but they draw lots of current) and that's the trend we see these days. And copper is expensive, so 4 ohm voice cois are cheaper to make than 8 or 16 ohm ones.  Enjoy the Music! 

If you decide to go both routes, start with your preference, listen a few weeks then the next. I changed several things at once back when I was getting serious about the hobby and had a hard time discerning what was helping what, etc. Cost me extra $ at first.