Fussing over a new cartridge installation


I have just installed an Ortofon Super OM20 on my Harmon Kardon T-45 turntable, and am enjoying LP's with an enthusiasm I haven't in twenty years. I have a couple of setup questions, though.
1. The H-K table has a "Capacitance trim" setting. I have found a capacitance listing for the cart, but no such info for the amp (an NAD AV713 reciever). Any advice about this?
2. After setting up the cart (which is an immediate and dramatic improvement on the worn old Grado that preceeded it), I learned that the Ortofon cart has a removable weight. The H-K "Microrace by Ito" tonearm is relatively light weight--would there be any significant benefit to re-installing the cart without the weight?
3. I bought the turntable second hand a few years ago, and the previous owner included a second headshell, from Audio Technica, which appeared unused. I found that the gold contacts on the H-K headshell were too small to fit the prongs on the ortofon cart, so I mounted it in the A-T (non-gold) headshell. It seems fine, but I'm just mentioning this in case there is some advantage to the original headshell or wiring that I should know about.

Thanks in advance for your reply.
bt0a20
Thanks again. It's sounding good--and a real joy to hear records that I haven't played in more than a decade. I'll leave things be, I guess. I looked at the owner's manual for the turntable and it doesn't mention anything about VTA: I don't see any problem on that front, so I'll let the HK engineering do its stuff. (I don't have experience with recent high-end turntables, but this one seems quite respectabally effective to me.) Thanks for clearing up the bit about the cartridge weight, and for your advice about the Ortofon upgrade path.

One more question, as long as we're at it. The original HK mat is a dense rubber--it almost seems brittle, I don't know whether that is age-related or not, as I purchased this unit used. Would a replacement turntable mat be a sonically valuable upgrade, or is that pretty much "snake oil"?
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