Please don't torture people that like classical and opera with a wimpy inefficient bookshelf... That's my opinion.
Do this:
Pi Audio 6 Pi Speakers: ($3500~ shipped I think)
These will have thrilling dynamics and good non-horn sounding vocals. They'll be alive, and squash little speakers. The only condition is they must be corners. But that's the good news, floor standing AND out of the way. They easily reach into the 30hz.
I would do this config:
Wood: Their choice
Finish: Their choice
Compression driver: B&C DE250
Woofer: B&C 12PLB100 (unless the Pi guy says it lowers efficiency, I would keep it 100db+)
Inductors: 15 gauge
Capacitors: Standard
Resistors: Mills
(
A review from someone who made their own at the bottom of the post)
Speaker wire Belden 9497: ($100? Maybe way less) There's no reason to terminate this wire, it's simple, easy, and they can order extra to trim to fit. It's out of the way. It sounds great, too.
Interconnects Belden 8402: ($60 x 2)Sound great, very inexpensive.
Options on Preamps/Amp/DAC:
This is where things are a little more complicated, I'll give a couple ideas.
Mapleshade modified Scott integrated tube amp: ($1800 shipped) The general actually pointed this out as a candidate for how someone could get into good sound without spending silly amounts of money. It has a built in phono & volume. Then get a
BorderPatrol DAC SPDIF only SEi ($1350). This leaves $200 left over to get any disc player with PCM output. For example
this Sony would be fine, the quality of the player won't matter, and if they want one that screws up the sound the budget doesn't allow for that.
Alternative to the Scott would be a
Decware Zen Triode (integrated: $1800) configured with stepped attenuator, two pair input.
BorderPatrol DAC SPDIF S ($995) and
iFi Phono 2 ($549). And any disc player such as that Sony. The total is a couple more dollars than $7000.
If they would prefer non-tube I can come up with some ideas but I think they'll be slightly less enthralled. I wouldn't change the speakers if there's no issue with corner speakers.