ProLogue Premium Features/Specs
With the flip of the switch and the rolling of the tubes the ProLogue Premium can go from the exciting power and rocking aggression of 40 W of KT88 tubes to the smooth and robust warmth of 35W of EL34s*, hence the amplifier is multi functional. Also a key feature is the Adaptive AutoBias circuitry which continuously monitors and runs each tube in its ‘sweet’ spot so as not to over stress the device. This protects the tube from failure and elongates the life span. The AutoBias on the ProLogue Premium is also designed to stay out of the audible signal path and the amp has a “soft start” by which it gently brings power to the tubes, also expanding tube life span. It takes about 15-20 seconds from the time you flip the power switch to the time you’ll hear music coming out of the amp.
Other nifty features include the Home Theater Pass Thru – which I did not test because I don’t have a home theater set up – and the BTI circuit which stands for “Bad Tube Indicator”. The BTI lights are located on the deck of the amp at the base of each tube so that if one goes bad there‘s no process of elimination, no fumbling. Additionally, the ProLogue Premium has a PTP circuit that will power off the amplifier if the transformers overheat and power cycle back on once cooled down. The OTP circuit protects the amplifier in case there’s a massive tube failure. This, combined with a +B relay circuit, will reset the amplifier once the failed tube is replaced and is designed in such a way as to interfere as little as possible with the audio signal. These features are advantageous in that this amp largely takes the guess work out of owning a tubed unit and can save you a hell of a headache and a dent in the pocketbook.
You’ll notice that while the amplifier is on the smaller side it is quite heavy. This weight comes from ProLogue Premium’s transformers, which are nearly as large as those on the flagship DiaLogue Series. More iron usually translates into better sound quality and musicality.
An interior inspection of the PrimaLuna amplifier could lead one to believe it was built by someone with OCD. The point-to-point wiring is meticulously clean, wires are braided and twisted with absolute precision and everything is clean enough for open heart surgery. It really is a beautiful and carefully built piece of equipment that puts so many other hand made tube amplifiers to shame. The bottom panel is even vented to allow for air to flow up and out of the tube sockets to cool the amplifier while operating.
The ProLogue Premium comes in a high-gloss, Black Sapphire finish, with either black or silver faceplates. There are four gold plated left/right RCA inputs on the back, along with the home theater pass-thru. Six 5-way binding post allow for either 4 or 8 Ohms impedance options. There is even an extra grounding pin on the back incase your wall power isn’t actually grounded. (Those of you in older apartments/homes, this is for you.)
On the face are two very solid feeling knobs. One is for volume and the other is input selection. The volume knob rotates very smoothly and feels compact, weighty, and pricy. It is a linear volume control that has a maximum gain of 37dB. The input knob appears to be software driven, so when you power cycle the amplifier it defaults back to the first input. This is actually my only real complaint about this amplifier. I often had my turn table on input two and would get everything all set up, assume the listening position, and realize I needed to pop the selector over to input two. (I didn’t use the remote while reviewing, but there is an input selector on it. – doh!)
While the amplifier was in my possession I ran the EL34 tubes and the 12AU7 with improved transformers that lower distortion at the front end. I paired the ProLogue Premium with the PMC TB2i monitors and used the Electrocompaniet PC-1 CD Player and Supra Sword interconnects and speaker cables. For analog I used my Rega P3/24 with a Moon LP3 phono stage and Sumiko Evo III Blue Point Special cartridge. I used the Granite Audio #570 power cable or the PS Audio PerfectWave AC5 with the amplifier. The differences between all the power cables I tried were very slight leading me to report that one doesn’t have to pair the ProLogue Premium with a super expensive aftermarket cable to get great sound from it.