Audiophilepure

https://www.stereophile.com/content/octave-audio-mre-220-se-monoblock-power-amplifier

Pre-measured tubes arrive in a separate box, with amplifier positions labeled for the power tubes. If you use these, you’re golden. If you want to roll tubes, manual bias adjustment is necessary. Turn the front-panel bias selector knob to the tube you wish to bias, then use the supplied small screwdriver to adjust the trimmer screw next to the tube. Yellow and green LEDs located between tubes V2 and V3 indicate if bias is too low, correct, or too high. Combinations of yellow and green allow you to tweak bias higher and lower according to tube choice and loudspeaker type. Sayeth the manual, “Certain loudspeakers may benefit from the higher bias current, as it will increase the damping factor and provide slightly better control of the speakers.” BIAS Low corresponds to a plate current of 33mA, and BIAS high to a plate current of 40mA.

The low end side of the spectrum is an easy bit to explain. Most powered subwoofers utilize class D amplifiers internally, and the application here seems to exemplify why. The bass response through all speakers demoed was tight and detailed. If you are looking for bass control, are a self-proclaimed bass head or find yourself with a proclivity towards dance or electronic music, you might find yourself in favor of the Naim Uniti Nova PE vs. the Star. There was slightly more bass energy overall, and things were much more controlled across the scene. Subtle nuances in low end instruments could be picked out easier, and there was just more low end information to ingest. Of all the bits and bobs about the listen, this was perhaps the clear winner for the PE version. If you are struggling to get the most out of your low end, check out the PE in the all-in-one category. The 150 watts is really able to provide the necessary shove for big drivers in that regard.

In terms of the big picture, the PE really seems to provide a lot of that same dynamic shove across the frequency spectrum. There is a palatable energy to the sound that could be viewed as more than the sum of the parts here. Compared to both the Naim Uniti Star and the 300b Woo Audio WA5, there was just a bit more thrust and metaphoric “crackle” to the picture. In one of my partnered listening sessions a friend played a very solid, relatively simple track featuring female vocals, some light backing instruments and no percussion. Upon switching back and forth between the Nova PE and Star the impact was noticeable and echoed confidently by the company. An experimental success of sorts from an enthusiastic, but relatively un-HFi-educated outside observer. This distinction took place despite the usual “Rage Against The Machine” track or high-drama electronia typically used to showcase this genre of sonic clout.