How long for cartridge break-in?

I would say a few hundred hours, which can be an eternity in the vinyl world. I have read that some cartridges take half their lives to break in. I have a cardas test LP with a continuous groove which helped me break in my cartridge. 2 hours on, 2 hours off, etc. I would say the most difficult component (along with phonostage and phono IC's,tonearm cable) to break in. Patience is a virtue.

Incereasing the VTA helps significantly. Not to wait for more burnin before I decide if I like the cart. If not, any recommended cartridges?

He re's some things nobody mentioned.
Sure, the DC Player may sound more dynamic, of course have a much lower signal-noise ratio, and knock the house down with more bass, without acoustic break up.

Measures can be taken to enhance these qualities I mention with vinyl playback.

Are you noting that you have to considerably turn up the volume when playing your vinyl rig? If so, then no matter what folks say, that hi output MC's work just fine with MM phono stages, there may be a possibility that you don;t have enough gain at the phono stage?

Generally, the big boys here know that very well, to not rely on an integral phono stage placed inside a pre-amp, no matter what the vintage-cost of the pre-amp, and choose a high quality external phono stage instead.

It's often a sad fact, that the road to nirvana with analog can cost some beau coup bucks. On the other hand though, wise folks may tell you that throwing money at a problem may not necessarily solve it. Mark

I would also experiment with the mat. I found the Herbies mat to work incredbly well on one table, but not sound as good as a stock felt mat on another. Also, I would give yourself some time to adjust to what analog does better than digital. You are used to listening to a very good CD player and it does a lot of things well.

Finally, I have found listening to be less enjoyable when I mix analog and digital. Try just sitting down quietly and listening to a record, rather than going back and forth to compare. That is really tiresome stuff.

Your problem is the Rega's lack of proper speed stability and its large amout of stylus drag. As for break-in, I suggest a very powerful 45RPM dance single with heavy bass modulation. Turn the volume down and play it over and over a few times each day. This will accelerate break-in tremendously.