How long can you go with a phono cable?

I agree with Rives, and would like to add that any cable especially phono are likely victims of RFI and EFI. This will be dependant on your system and enviroment. But I thought it might be a consideration in your decision.

The industry standard is 1.25 meters in length, although we have made cables up to 2 meters in length that have worked very well in this application. As a matter of fact we once had a gentleman who needed a 3 meter run and we were just as supprised as im at how good it worked and sounded.

Until it finds out that you've been also making good music with a 0.5m orchid digital w/XLR ends!

I agree with Rives and Theo. Don't forget about shielding, very important on a phono cable