My Level 3 upgrade arrived Friday and I have spent a large part of the weekend listening to music. The total turn around time was eighteen days including shipping from the West Coast to Maryland and back again. Fortunately I was traveling during much of that time.
I let the system play for twelve hours before I started any critical listening. It is very difficult to compare the Level 2 versus the Level 3 results without having them side by side. This is the same issue I have had comparing power amps, speakers, preamps, and DACs. I expect I will have the same difficulty as I upgrade my streamer.
Fortunately, I anticipated the issue and had notes regarding particular songs and source material. Across the board I found the instrument and performer separation was improved. Frequently the singer, or featured instrument was brought forward slightly. Stage presence height improved with Level 3. Level 2, plus all my other preamps over the years had exaggerated placement relative to what they should be. Level 3 is the first preamp that I have owned to nail the height issue. Things that are suppose to be overhead (think Pink Floyd, soundtracks with singers on different floors, and helicopters) are where they should be. The soundstage placement is consistent a joy to listen to.
Regarding background blackness: I am not certain I can tell if there is an improvement, or even a change. There might be, but I am unable to identify it.
Some instruments seem to have a more natural extension. The Level 2 improved this area versus the Benchmark LA4. The Level 3 is better than the 2 with this as well.
Bass is more accurate in the extreme (under 30 Hz). The extreme bass in Imagine Dragons' "Radioactive" is actually tamed a bit. I didn't have to rush to turn it down because the house was shaking. The house still shakes with the cannon from The 1812 Overture as it should. Bass placement is a bit more detailed and tight.
I am very glad I decided to the get the Level 3 upgrade. It compares favorably to the Backert Labs Rhumba Extreme 1.4 (have not heard the Rhythm 1.4).
Regarding tube rolling: I have the original NOS tubes shipped with the unit plus the Ray Reserve and Gold Lion tubes LTA offers. The upgraded tubes still sound much better than the standard tubes. I am not inclined to try many different tube pairings. I will leave that with the pros, in this case LTA. I did enquire regarding the Ray Select tubes LTA is now offering in place of the NOS Gold Lion. The replied that there would be a slight difference, but not much and that is could be perceived as an improvement or a downgrade depending on my perception. I may buy a pair down the road, but not the immediate future. There may be better tubes out there, but that is not path that I will be exploring for now.