The $10,000 Question

for low level listening i'd recommend something that is hi sensitivity and efficacy,  most tend to get up ago go at lower volumes much better and earlier.  you can also save money on the power amp section as it opens the door to lower power integrated amps. 

If you like tubes there is a whole world of lower powered amps out there that are very good for reasonable money, if you have the speakers for them, i.e. 95db-8ohm and up. Most horns fit this bill with many other type of designs avails from regular box speakers to open baffles ( OB's maybe a little unfriended to your wife). 

some Klipsch Heresy's mk4's ( maybe the Forte's)and a nice low powered SET tube amp can do some great things for a classical lover in a smaller room and lower listening levels.  there are other similar set ups out there as well. 

I’d consider the Quicksilver audio integrated built by Mike Sanders. It’s $2495 which leaves you left with a remaining budget of $7500 for speakers. 👍

Thanks for all of the advice.  I've got some speaker and amp pairings to look into.  I'm surprised nobody mentioned Raven and a good matching speaker.

Since you classical I would definitely consider Sonus Faber.  I have a pair of the Lumina Series bookshelf's.  Solid bass for their size and if you pair them with a previously owned McIntosh (space permitting) you may have enough left over for a REL sub.  McIntosh and Sonus Faber play very nice together.  If McIntosh won't work you could try Rotel.  I also have some Rotel equipment and they often have some "scratch n dent" products discounted off of their regular price.  I have some Rotel amps and also integrated.  If you go this route you could spend less than $3K on a decent integrated and have more $ for speakers and definitely room for a sub.  The only missing piece is tubes so if you decide to go solid these are some ideas for you.  

Let us know how you make out and good luck.

1. work hard to fall in love with some efficient speakers

that reduces power needs, ss and easier to try/use tubes in many ways:

less power needed; size, placement (remote control beam), weight, heat, cost, availability of options.

2. integrated with pre-in, i.e. pass thru without it's volume control, ....

I want both remote volume and remote balance (and mute). you often need to download the manual to find what hidden options are available, and which ones are accessible via the remote.

3. consider a future vintage preamp loaded with 'old world' features. budget a rehab for vintage.

4. used will definitely get you more, verify everything, patience to wait for what you want, hopefully find near enough to meet seller half-way or audition at seller's place.