Advice on Tonearm/ Cartridge combo


I've recently started using a SME 309 Arm on my SME rig, which is pretty low mass arm (9.5g).  The only cartridge I use and have is a Koetsu Black Goldline, which is a very low compliance cartridge around  (5 X 10-6cm).  I've been trying to make this combo work but these two just don't work well together, there's some resonance and distortion, especially with heavy piano chords.  Obviously I have change either the tonearm or cartridge.  Does it make more sense to get rid of the low compliance cart and get a more suitable cart to go with the SME arm, or should I trade in the arm for a heavier one that is more compatible with more carts.   

 Thanks,
J
tyan42
FR64S is a great suggestion. Also the Audiocreative Groovemaster II for a new high mass arm.
Koetsu Black Goldline is superb on my Origin Live Conqueror arm. Absolutely no problems with anything, anywhere, ever. Before the Koetsu, it worked wonderfully with a Benz Ruby. 


With such a light mass you definitely need a high compliance MM/MI cartridge, try some decent vintage cartridges and i'm pretty sure you will be impressed. Look for the best possible stylus profile and a nice cantilever, normally top quality MM/MI from the 80's are very nice. 

Or change your tonearm to something like FR-64s (very high mass) for low compliance cartridge. 
What were you using with that Koetsu, before the SME?     Were you enthused, with the Koetsu’s presentation, before the SME?      I could be wrong, but- it appears to me, that there are more good(as in, "upper tier"), higher mass, arms out there, than high compliance cartridges, from which to choose(though the aforementioned Kleos should be a nice match).      It’s also possible, that a used arm would be easier to market, than a used cartridge.     Does anyone offer a method/kit, to up the effective mass of that arm?
I had issues with Grado's Reference cartridge with my SME 309. Every time I would play one of those 45 rpm LPs, the first minute or two were unlistenable. I replaced the Grado with an Ortofon Cadenza Bronze and it was much better. Now I'm using a Lyra Kleos and love the combination. No distortion with either the Cadenza or the Kleos.