Moved from medium attic like room to larger room, everything is too bright

Audio companies make a lot of money on audiophiles who don’t address room acoustics, and instead go on endless rounds of gear swapping. You would be amazed what a few bass traps and decorative wall panels can accomplish. The latter can be custom made with your own images if you like. GIK sells them as "Art Panels." Or for plain fabric, Guilford of Maine can supply thousands of fabrics for use by most major acoustics vendors (RPG, ASC, GIK, probably others). They are guaranteed to offer something that will be not just acceptable, but fantastic with any decor.

Bribe the partner with whatever will do the job. Need I say more?

IMO, furnishings and artwork accomplish as much as acoustic panels which have a cheezo pseudo art quality.

To be effective, bass traps need to be  H U G E. A typical control room would have traps front and rear equaling close to 25% of the room volume. Most audiophool bass traps are wishful thinking.

...I agree....also, try moving the speakers closer to the wall (etc)

and if it's your garage that's been converted why would your other half care she doesn't have to go in there if it's the garage tell her that's your stereo room she's got the rest of the house to play with try getting Townshend podiums underneath your speakers they seem to get rid of all room problems because they stop all the vibrations from going into your speakers and to the rest of your equipment and also they get rid of the constant Earth vibration as well that shakes your speakers all the time.

Damp that space down before any speaker swap.  The space is acting like the interior of a speaker, so some creative room treats will tame it from being shrill.

Sq. root of 450 sq. ft. suggests a square space with the ceiling 1/2 that.

*Ick*  Pad the cell, and even the KLH will behave. *G*