Interconnects for tube equipment?

Pap, it all depends upon yr musical tastes (system synergy will come with trial of different brands). IMO, you should turn to used cables. A fast, silver cable would be my choice for tubes: the idea is, I have euphonic sound (tubes) but I need to extract absolute clarity in the bass & the upper register, & not lose one iota of speed.
In my tube days, I have used bearlabs, Nordost (SPM & Valhalla), Siltech & others to good effect.
Finally, do give some thought to the power chord; tubes can benefit from these... Enjoy!

Synergistic research makes an interconnect that would fit your system to a tee the Looking Glass Phase 1. Excellent on tube equipment.

I would definitely suggest Tice interconnects. It's two straight 14 ga solid copper cores for the (+) and one for the (-). This design gives very strong bass and clean, articulate highs. For the price George is selling them (1.5m pair @ $137.50) you can't go wrong. Someone who's very knowledgeable on cables told me the Tice gives 90% of what the Cardas Cross delivers...