A friend from the audio club was over yesterday. We listened for a couple hours and then put in some new tubes that just arrived. I know the Electro Harmonix "gold pin" tubes are said to come out of the same factory as the original Sovtek, but they are considered better from many of the reviews I have read. I paid a little extra to get Upscale Audio's Audio Research Select Grade tube. But, I have to say it was worth it.
We listened for an hour or so, not even burnt in yet, just the very slight burn in Upscale puts on them, and we both said.... wow... what a difference. We were both surprised. I did not expect to hear much of a difference, yet alone a big difference, but we both heard a very big difference. Much smoother... he actually commented that the one thing he was not completely happy with the LS17 SE is that he felt it was missing some of the smoothness that my STP-SE had. But with these Gold Pin tubes he commented that it smoothed out and the one thing he did not like was now excellent!
We are both going to suggest to our other friend who has one of these pre-amps that he might want to try these tubes.
The one thing that I have been most surprised with on this ARC pre-amp is how it appears to be more affected by these "tweaks" then other equipment I have owned. Switching power cables was a more noticeable difference then any other piece of gear I have owned. And now a seeming slight upgrade tube and it is a fairly large difference. This leads me to conclude that this pre-amplifier is much more revealing of slight changes then any other piece I have owned.