what speakers to use

So many variables. I have a similar size room that I used my Proac Super Towers in. They have a huge sweet spot as they are big time sound stagers and imagers. They will fill the room with music that is articulate and easy to listen to. I ran them with Quicksilver mono blocks for years and they didn't sound etched, but were very detailed. Let me know if you have interest, but they still sound better than so many of the speakers in it's range and since it's used, the price is a bargain. All speakers will have a sweet spot. Once you get into the room itself, that sweet spot will be gone regardless of what you get. I think it will still come down to what type of music, how loud you play it and how refined you are expecting it to be way off axis.

There is a pair of OHM 2000's in Walsh 2 cabinets currently up here on agon that appears to be a steal for $600. That's what I paid here several years back for a local pickup of older 100S3 drivers in teh same cabinets. That I use currently in similar scenario at home (see my system pics). Shipping could be tricky but worth it if done right. The beefy tube amp should do quite nicely.

I reccommend Tannoy Loudspeakers. My room is 16.5' X 34' with cathedral ceilings. I n my case, I built a custom pair using vintage 12" HPD drivers (ca. 1975), with premium outboard crossovers.

I am able to fill this room to great satisfaction with an SET 300B amplifier. Although my speakers are well out into the room (about 5' or so), Tannoys are used the world over in many varying situations with grear success.

Regards,
Dan