I'm really, really happy with Alpha-core MI speaker cables connected to my Threshold S/500 series II amp. Thanks Sean! I'm led to believe that the supplied RC links (Zobels) are absolutley required with Threshold amps. I don't know for sure, but I suspect these cables may be even better on a pure class A amp such yours. Threshold used to market speaker cables called "Weber Wire". These were multi-stranded speaker cables braided in a flat fashion. There is a reterminated, 1 meter pair currently for sale here on Audiogon. Other than that I don't know much about them.
I don't have any personal recommendations for interconnects. I have been told by a fellow Audiogoner who collects Threshold gear that Tara works well. Another Audiogoner who's had a lot of experience with Threshold recommended DH Labs. Jon Soderberg recommended Kimber,Cleartone and DH Labs. He also said that the Threshold's are reputed to be sensitive to power cables. My own limited experience confirms this. Jon sold me an inexpensive power cord that worked much better than a much fancier looking one I had on loan. In all honesty this may have been due to the fact that the female end was less bulky and therefore was not pulling itself from the amp like the fancy heavy duty one. While I have not tried these power cords myself; on the low end of the price scale the DH Labs and on the high end of the price scale the BMI's have been recommended.
Please share your findings. I for one, am most interested.