Do I buy an upscale TT?

Stick with what you have! The 301/Tri-Planar/Grado Epoch is truly excellent - and very costly! Spending more $$$ beyond this is a waste of money! If you want to hear a real change buy a better pair of speakers.

IMO, the turntable is the most important part of the vinyl system. You already have a fine tonearm and cartridge - let them sing! Be sure to audition an air bearing TT, air thrust and air sleeve. Air for both, if you can find one.

Once you have heard air, there is no going back. IMO.

But others like Mike Lavigne also have very good advice.

@Mglik

You have had some good advice from colleagues above.

I would like to add that what you heard was a total system, including room dynamics, acoustics. Please do not underestimate the impact of room treatment, simple adjustments to your current room (furniture layout, alignment of speakers, sound absorption of curtains / wall sound absorbers etc) will yield surprising results without change of rig.

My friend bought a fully refurbished Garrard 401 with some upgraded parts, with a very nice plinth, fitted with a Groovemaster 12" and an Ortofon SPU Royal GM II.

For some reason he had to go back to his other turntable which was Nottingham Analogue Ace Spacedeck fitted with the same arm and cartridge.

Let's just say the Nottingham Analogue wiped the floor withe the Garrard 401 in everyway possible.

Whilst I understand the nostalgia in owning a Garrard 301 or 401, and for those of you that own and love them fair play to you, but from my experience they cannot compete with more modern well engineered turntables.

To get good sound from a Turntable requires a huge investment. Unless you really want to spend over 50-200k you will never be happy chasing dragons.

sell you turntable like I did and focus on digital and getting a better amp and speakers first. Or buy a Kronos Sparta for about 30k-35 with a good tonearm and get a 20k audionet phono stage with a 10k power supply for it. You will also need Kubla Sosna elation tonearm cables and power cables.
All this will not be perfect but will be a step up from what you heard in your friends room.