I have been using headphone systems for fifty years (the top of my head hurts from remembering the Koss headphones… ouch). I got really interested in high end headphone systems about twenty years ago. You can see my current headphone system under my user ID. I was listening to it just this morning and was simply stunned at the sound.
I have Bose QuietComfort and I love them on airplanes and while traveling… but they are cartoonish and simply terrible in terms of High-Fi. Blu-tooth sounds terrible.
First of all, I can assure you headphones can be absolutely stunning. They will not replace a regular audio system… but, as in your situation… wanting to let your partner sleep… they can be wonderful.
I would stick to wired for your test. Bluetooth is terrible. Once you know how wonderful they can be, then you can decide how to proceed.
Lots of high end preamps have headphone jacks… many sound simply terrible. They just throw them in, without thought. The best system is a separate system. But, you are not there yet. You are testing the waters. I would recommend a set of Focal headphones which are plugged into your Mac as a start. Focal are very efficient… so will sound pretty good.
To escalate, you probably want a good headphone amp… I recommend a Woo. Their tube headphone amps are incredible… warm, natural and dynamic… the more you pay the better they sound. I own a WA6, WA6SE, and WA5. I recommend any and all.
Headphone systems are exactly like main systems. Every component maters… and the sum of the parts equals the whole. The good thing is you can put together an incredible headphone system for a tenth of the price of a main system. Well, worth having both. For me, sitting in front of the fireplace while listening to music on my headphone system is wonderful.