What I am wondering is, is a high quality tube amp as likely to present as much of that subtle (or not so subtle) holographic magic if the source is digital?
The right tube amp or preamp can help your system, with digital source, to sound more holographic than it sounds now. However, holographic sound depends on much more than having a turntable or a tube amp. It’s a whole system/setup/room combination.
What DAC are you using? The wrong DAC can sound two dimensional. Having your speakers too close to the front wall can do it too. Those are two of the cheapest and easiest potential fixes I can come up with off the top of my head.
I would start a thread, or search for one, on how to obtain holographic sound. It would be very helpful if you post pictures of your system and room in the Virtual Systems section of Audiogon and list all your components, including speakers. Also, tell us what you like and dislike about the sound you have now and what improvements you’d like to hear.
There’s no simple answer to getting more holographic sound, although it’s possible to chance into it by inserting a new component into your system. More likely it’s going to take more work than that, though.
I know you’d much rather get a simple answer, but I don’t have one, anyway.