Good luck on sorting this out-you'll get lots of good advice but it will be conflicting as we all have a different experience. My advice should be filtered through that lens, like all of it-its a very subjective hobby.
I agree with those who say you'll be disappointed to go cheap on the preamp-components should be well-matched or its the lowest common denominator that prevails.
I would prefer a well-designed and well-built integrated over mismatched amp and pre. Integrateds are, in my opinion, closer to separates than was the case in years past. A couple of brands that I have personal experience with-be careful of recommendations from folks who haven't actually heard the products-Anthem and Michi.
Anthem builds really good stuff for a fair price. You could get an Anthem pre and amp for around your budget. I suggest taking a look at the Anthem STR Integrated. I owned that unit at one point and it was excellent. It is built to last-not cheap build at all, has plenty of power that your speakers will appreciate, a competent DAC and phono stage-everything you need for $5k. It also has the ARC room correction which tunes the output to your room. This leaves you with the budget for a nice turntable, arm, and cart.
Michi is the upscale version of Rotel-separate design teams, higher quality components, etc. Also in your budget-you have lots of choices for 10k.
I share your anxiety concerning buying used. You can save money and likely won't have any issues. But if you are unlucky, it won't be a good experience. TMR is a good compromise. You will pay a little more for used perhaps, but will get a 30 day return window (5% restock fee) and 90 day warranty. I've had 4 transactions with TMR-all good.
If you can visit a couple of dealers or a show and listen to different options, well worth the effort.
Good luck!

