System forclassical music

Many possible combinations for the front end, but for speakers I'd suggest Magnepan.

Get the Dutch & Dutch 8c speaker system.  Just add an iPad or laptop and you're done.  Built-in amplification, DSP EQ, active crossover, etc, etc.  Absolutely astounding sound.  Some of the best I've ever heard at any price.  Wonderful for acoustic and classical music.

New retail at about $12k.  When you find them used, around $10k.

If your classical music friends are also regular orchestra concert goers, I think that whatever speakers they decide on purchasing, they should be speakers with good "imaging".  It is probably a characteristic that they would not think of seeking out, but that characteristic would help more closely reproduce the experience of listening in a concert hall with which they may be familiar.  The physical setup of most symphony orchestras varies very little from orchestra to orchestra, whereas the instruments on "Pop" albums are wherever the recording engineer chooses to "pan" them.  Good imaging will showcase that reality.
A comment about subwoofers in classical systems :  I spent over 30 years as a performing classical musician and can honestly say that I never heard the magnitude of bass that many audiophiles consider to be appropriate on an orchestral recording ---- and I was sitting right next to the double bass section !  I think that the advent of the "Electric Bass" on pop recordings gave the impression to some that the same powerful bass response that an electric bass is capable of rendering at the twist of a knob is also possible on the traditional "stand up" contrabass typically found in a symphony orchestra.  It is not possible ---- nor desirable.  They are two distinctly different experiences.
      If the fore-mentioned classical music friends are simply wanting to wander about the house bathed in classical music [ as I can confess to doing every day ], their "in-wall" system should be fine, but if they want to go that extra step into our "Make Believe Concert Hall", they should spend some time researching the joys of entering the audiophile world.
What a great hobby !! 

I have a season ticket package for the orchestra and it's true we don't get the magnitude of bass that audiophiles expect. But there are the passages performed by tympani which at times can sound like rolling thunder (high school tympanist here). Also, the contrabassoon reaches a lower octave that can be reproduced on a revealing HiFi system. There are these moments that I miss since I don't use a subwoofer with my floorstanders. Same with organ recordings, I know I'm missing what I heard at the concert hall.
The tradeoff is that my speakers image so well and realistically I can enjoy the experience without hearing the lowest octaves.

Buy a basic used system. $10k can go a long way used. Forget streaming. Play your own music on vinyl and cd. That’s good enough.