The AR turntable

I doubt if you will improve on the table for the amount you mention. I would concentrate on small upgrades like building a good support for it if you dont have one and eventually upgradeing the cart. I use SME arms myself but have used Rega and they are good arms. I am not sure the difference would be audible on the AR and it would certainly not be cost effective.

Ignore the negative comments on the Rega arms. It is a solid arm offered at a price that is an incredible value. I've heard literally dozens on these mid-80's ARs.

Dave

I sold my AR ES-1 just a couple of years ago, purchased new in mid-1980's. It definitely has a warm, musical sound, deep but slightly soft bass. Personally I love turntables with suspensions (many don't) for their palpable and musical sound. I'm trying to remember why I sold it..... I do have a $6000 rig based on Basis 2001 which is substantially more neutral and detailed while still quite musical. However it was a stuggle to find a modern turntable that was satisfying musically while also achieving a substantial increment in sound quality.
Art

The AR is a solid tt. I owned one with a Premier MMT arm for a few years. I replaced it with a VPI W19 MK3 with Grado arm, and in my opinion the overall improvement in resolution, bass extension, and overall refinement was very significant, and not subtle. What the AR did have, in comparison, was a nice sense of drive, or prat. But the soundstage was smaller, the sound less weighty, and a little cloudy in general. I would rate your Rega arm as superior to the Grado arm; so add that to the mix. A friend has that HW19 with a Rega arm, and the sound is very good. IMO, in a different league than what I had with the VPI/Grado combo.

My advise would be to keep the Rega, and mount it on a VPI HW19 Mk3, or better yet a MKIV. For an investment of well under $1000, you will realize a very significant improvement in sound.

Good luck.