How much do you have to spend?

Room configuration and speaker placement necessities are key to system synergy. You can have great gear and still fall far short of excellent performance. Your amp is said to be a weak link, but to me trying to get a full musical picture from a pair of 5” woofers is not a realistic possibility. Within your constraints, add cone area!  MoFi SourcePoint 8s are a good option. And use Dirac Live to create a fully integrated in-room response with your subs. 

1st rig ($6k): $1.5k speaker, $1k amp (used) / preamp, $1k Dac, $1.6k streamer & $0.9k cables.

2nd rig ($5k): $2k speaker, $0.7k int. amp (used), $1k Dac, $0.6k streamer/lps &0.7k cables.

Yes you can easily put a good system for 10k. My friend spend 10k , Galion Amp tsa 75 $1500, galion tsp preamp $1805 , Focal floor standing speakers for 3.5!k, advance Paris cdp $1400.plus cables and cabinets and room acoustics.It sounds. It sounds good to my ears.He does not care about diminishing returns.

I divide my system approach into 4 groups. Analog, Digital, Power, and Speakers.

Digital is centered on a good DAC - $2k - Streamer and CD Transport - $1.5k

Analog - Table, Arm, Cartridge, Phono Stage - $4k ( about $1k each) new cart.

Speakers - $1k to $3k Used

Power/Pre - so many great used older high current Class A/AB - $2k

$10k to $12k total for a very. very, nice system.

There are diminishing returns and there are values.  When I bought my first external DAC years ago it was a Denafrips Ares II.  Made a huge change to my system.  I caught the bug.  Year and a half later I purchased the Pontus II at 2x the money.  Was the Pontus II twice as good as the Ares II; I would say not but was it worth it; I say definitely yes.  The improved sound was not linear to the increased cost but the improved sound had definite value to my listening experience.

I could make comparative equations across most electronics in my humble opinion.  How one would do this with loudspeakers is beyond me.  A $5k system can be really really good.  Would a $10k be twice as good or $20k be four times.  Probably not, yet does the increase expenditure increase the listening pleasure; does it add value to your experience?