I own the LTA preamp (upgraded to L2). When I asked the same question of Nicholas of LTA, he said their power suppliers are very good at filtering (David Berning is an excellent designer of power supplies as well as the ZOTL circuitry) and that the stock power cord should be fine. I am using a Puritan Audio Labs standard cord as I prefer a shielded cable, and it works great. In the past, I’ve also used an Oyaide Black Mamba Sigma II with similar positive results. With these cords, I can easily tell the difference between L1 and L2 preamp and also the benefits of upgrading the 12AT7 tubes to NOS Siemens 12AU7.
