Headphones are always a practical choice to prevent noise bothering neighbors and to get around problematic room modes, but IF I had a $10,000 to blow just on audio to chances are I'm probably in a position to use speakers:
Speakers : Focal Electra 1028BE, $5,000
Amplifier : Unison Research Secondo, $1,500
Source : Opera Audio Consonance CD120 Linear, $1,000
Cables, etc : <$500 for analog IC+speaker cable (BlueJeansCable?), surge protector, DIY platform for CDP and amp
Acoustic treatments : Roughly $500 (basic room treatment - DIY diffusers) to $2,000 (if in a flat, requires some sound-proofing)
---
Or if I'll have both speakers and headphones:
Headphone : Audeze LCD-2, $1,299
Speakers : Swans M200MkIII, $399
DAC-HP-Pre : Meier Audio Symphony, +/-$1,000
Transport : Custom, small form factor PC* I use at home - if it counts in the $10,000 audio budget, I'll put in about $1,500 for a fully customized aluminum chassis with AMD A10+16gb RAM+SSD+HDD
Cables : <$200 for digital and analog IC
Power : Around $300 for UPS+surge protector
Furniture : <$1,000 Custom, really solid, fixed table; comfy office chair
*With 240gb SSD primary drive for Windows and latest Total War game; music stored on secondary, quiet operation 500gb 7200RPM drive
I'm still way under $10,000 here