How much do you need to spend to get digital to rival analog?

Yes zalive, it comes down to the master. But better is better. We have no control over which master is used. 
The question is, is computer audio better than digital playback from a CD drive. I can not really answer that question. I have compared the original CD to its copy on a computer (Apple Mini with Pure Audio) and I can not tell the difference and the computer is up sampling to 192/24 the player is not. A down loaded Hi Res version does usually sound better than it's CD counterpart but again are they using the same master? 
I am more than happy to get rid of all my CDs. They are now all on the hard drive, what a PITA that was. Gives me more room for records:) I have nothing bad to say about computer audio. I love the degree of flexibility you have with Pure Music which uses iTunes library to organize the music. The whole set up cost me about $5K. The Mini, a 6 TB hard drive and a Berkeley Alpha USB. This is about the price of my cheapest cartridge so from a price perspective digital has it all over analog. 
I only buy a CD on rare occasion when music I want is not available to download. 
Geoffkait with two F's, Michael Fremer's opinion is not one I would rely on. His hearing is way better than mine and your's for that matter. He can hear the "dramatic" difference between a $100K turntable and a $400K turntable. His use of superlatives boggles the mind. I can't even tell if he likes music. 
Geoffkait, I'm worried about your ears. Cassette tapes suck. I have a Nakamichi Dragon up in the attic you can buy from me if you like. I bought it to record cassettes for the car before CDs became available. 
I'll bet you are an 8 track fan!
Fleschler, I only have 2,348 78's  

Mijo
I will buy your Dragon.
It can join my zx7 and 660zx.
Cassettes suck?
What a preposterous blanket wet noodle statement but how come I am not surprised.
I invite you to an evening of cassette tape playback on my rig with some of my tapes.
Of course some tapes suck, just like some vinyl and some CDs etc etc.

I used a Tandberg 320? and a Nakamichi zx7 for recording live choirs in the 80s along with a Tandberg 9000 R2R.  The DAT deck was superior.  However, the cassettes I made were of superior quality to nearly all prerecorded tapes.  There lies the probable cause for the previous posts.  Prerecorded tapes generally were awful compared to LPs and R2R 2 track or 7.5 ips 4 track.  Premium cassettes recorded at home or live sounded good.  I got rid of about 500 cassettes and kept only my live recorded tapes. 

Mijostyn-good for you, another audiophile interested in the music first although 78s can be very dynamic if frequency rangebound.  They are direct discs with perfect non-edited take credentials.  My 78s go back to 1900 so stylus size, speed and equalization make it more cumbersome to listen to.  It's an active hobby to listen to acoustic 78s (pre-1925).  

Uberwaltz, I am thrilled that you like to watch little reels go round and round but even under the best circumstances cassettes are colored and bland. If you turn the dolby off they sound better but noisy and the worse kind of noise is the steady state stuff like tape his. There is no way you can win but back in the day it was the best way to get music in your car and in a way they are better than CD's because they are harder to damage. One good scratch in the right direction and a CD is worthless.
Played back on the Dragon they are worse than MP3 files. If you like to listen to then for nostalgic reasons wonderful, that is why Howard Johnson's made 23 flavors.

Then send the Dragon to me.
We all have opinions obviously but you should avoid silly blanket statements that you cannot substantiate.
Sorry but I do not watch the little reels spin whatsoever, too absorbed in the sweet music.
No nostalgia involved, just music on a grand scale.
As I said I invite you to listen to them on my rig......