Speaker upgrade for classical music

Give a chance for active monitors, first of all: Neumann, Genelec, ATC.

I have now a Graham LS5/8 in my second system, really fantastic, organic, big, natural.
But I love my older big professional main monitors and can recommend everyone to try them.
Professional gear often offers more sound for the money, and active monitors can designed for better matching between amps and speakers/drivers.

You need speakers that can deliver scale, dynamics and accurate instrument voicing primarily.  Maggies are ok but can lack dynamic freedom needed for large scale orchestral.  B&W 800 Diamonds deliver detail of Maggies but also enjoy being pushed...huge soundstage and dynamics are easily handled!

Agree 100% on B&W. For room of your size 802 model will be the best. You should be able to find 802D or 802D2 under $8000 on used market.

If you have $4 - $5 grand to spend, with your electronics and desire for classical music and midrange, you really need to consider Sonus faber Sonetto V’s at $4,999.00. Quintessence Audio in Chicago is a great dealer with good demo capabilities and knowledgeable staff. They may even have a demo pair at less money. The Sonetto’s are easily matched with amps both SS and Tube. I have owned Luxman, and Rogue Audio amps and Focal, B&W, Yamaha NS 1000, and finally Sonus Faber Venere 2.5 and now Sonetto V speakers. While I don’t have a $100k system, mine is a $15k system. I’ve had friends with $70k systems say they can’t get the sound that I have. I can only agree that Dynaudio, Monitor Audio and the many other suggestions you’ve received are good speakers, but you’d be selling yourself short if you don’t at least audition the Sonetto V’s. Good listening and good luck!

I've never liked Polk Audio loudspeakers.  Big cabinets stuffed to the gills with cheap drivers and sold for cheap.   They look good, but...

Your very best value is in a good DIY loudspeaker project, or possibly finding a well-made DIY set used.  Don't turn your nose up at DIY.   Many of the designs are done by the best audio engineers on the planet and are just as good as the best commercial designs.  Within your $8k budget, you could easily put together the Linkwitz LX521 system and never want another speaker again for the rest of your life.  Will stand up against the top line $100k MBL system.  

The LX521, properly done, has no need for sub-woofers.  This is a project you could readily afford.  They do come up on the used market from time to time, but they're so good that few have a need to part with them.   The primary drawback with the LX521 is that it uses an active crossover and multiple power amps, so it's a considerably more complex project, but many have built them and you WILL be the envy of every audiophile visitor.

Another DIY project is the SEAS Thor.  Total materials cost will run you about $2500.  If you don't want to build it, Madisound partners with a cabinet maker that will make it up for you and ship it to you.  Delivered will probably run you about $3500.

The Thor was designed by Joe D'Appolito, one of the best known loudspeaker designers on the planet.  This is not some cheap throw together.   This is true audiophile hi-end.  This design is very comparable to the Joseph Audio Perspective 2 Graphene, which retails at about $13,000.  Both designs use the same tweeter and have transmission line cabinets.  The Thor uses a slightly larger bass driver.