1 TB would fit my 1000 CD collection, but not my husband's 15,000 CD collection.
With 2:1 lossless compression, we would be talking about 5 TB. 10TB without compression.
Using 12:1 lossy compression, 1TB might do it.
Even then, if such a device existed, I don't see how you could select which folder/file to play.
A few buttons on the front wouldn't be adequate for that - these controls work fine for a single CD since the device controls don't need to handle the album selection (that's done by the operator who chooses which disc to insert), just track selection.
But for a music collection, you would require some kind of display.
Since there is unfortunately no video input on the Bolt, one would need to a device with an additional display.
Such a device would more accurately be called a player, not an enclosure, since it would need to read the content of the hard drive, decode the file system, playback the files, and do a D/A conversion for the the audio signal.
You are basically talking about a laptop computer with a large storage amount at this point. It would be bullky and inconvenient to use in the car. No doubt such devices will shrink physically over time as technology improves, but given the physical constraints of the Bolt Gen1, the requirement for an additional display would remain.
Since the firmware in the Bolt cannot deal with a collection that large - even my 64GB stick in lossy format is too large for the Bolt - a pure storage interface cannot work.
And all this still presupposes putting $11,000 of labor into transferring the entire CD collection to a hard drive. Yet again, this is impractical.
I found a player unit that is similar to the one from Germany, but in the US. Same half-DIN form factor.
http://www.qualitymobilevideo.com/ad318.html
https://www.myronanddavis.com/ad318
Specs don't explicitly list CD audio support, though, which is a bit strange, but they list CD-R and CD-RW. Would be odd for it not to support audio CDs. I sent an email to the manufacturer to inquire, but it bounced. I sent another message through their web site.