ARC VS-115 6550's or KT120's

Hello everyone, this is my first post for open opinions.    I recently updated my power am from a Jolida 502P to an ARC VS-115.  The Jolida was modified with Level 1 and Level 3 Mods, not sure what that meant, but I got a good deal on it from a fellow Audiogon member and its served me well.     I wanted a bit more power and openness and I sure got it with the ARC VS-115.   The rest of my system is as follows.   REGA RP8 with Hana SL Cartridge.  Im using a Sim Audio LP5.3 with the outboard power supply,   PreAmp is ARC LS16 Mk2,  Interconnects all around are Signal Cable Silver Resolution and speaker wires are Anti Cable 3.0.   Speakers are Spatial Audio M4 in red with spike feet.   OK, so here is my big question.    The ARC VS115 came with new 6550 tubes, my Jolida 502P was using KT-120's ,  I know apples and oranges.    My thought is , am I missing out with the VS-115 by not using a new set of KT-120's, or should I just use the 6550's for a year or so because they are new.  I hate to waste new tubes, but I am curious if anyone has made the upgrade and how was it?   Im not really concerned about the price of the new tubes, its more about wasting the 6550's,  because lets face it,  if the KT-120's are that much better, why would I ever go back to 6550's?     Thoughts?    Thanks.