Raal/Requisite PDT-1a Review
"Received it yesterday, 20 July 22, from HeadAmp and I appreciate the quick shipment and excellent packing. This is my first non-hybrid tube amp so my comparisons are limited. I like the solid build quality and love the size/smoothness of the volume knob. I've read that toroidal transformers do well in reducing background noise (hiss/hum or crackling) and I'm pleased to notice it is working nicely on the PDT-1a. I don't hear anything when dialing up the volume after pausing the signal. I’m running it from NAS through a FiiO-K9 with the ES9038PRO processors. Looks like the tubes are the Russian versions from Svetlana. The ZMF Atrium and Fostex TR-X00 sound fantastic with the spaciousness and holographic staging. The sound is full and expansive across the low-to-high ranges and loud enough for me at around 10 o'clock on the dial. Also did a quick check with the Sennheiser Jubilees and 80-Ohm DT-770 Beyerdynamics and they sound great too. Safe to say dynamics respond very well, but my planars on the other hand, sounded weaker on this amp. The LCD-2C seemed blunted/kind of muffled. Even worse on the Ether CX and the Aeon Noire and they became distorted as I approached 50% on the volume. Maybe it's my planar models that do not work well on it and perhaps it could do better with more sensitive planars? I did have one other set of planars that responded better than the LCD-2C and DCA's on the PDT-1a: Monoprice M570. It has the same magnetic drivers as the Sendy Aiva and a Sivga model with a lower 32 Ohm impedance so that could be the reason. Still not as magical as dynamics that synergize much better on it. I notice the same weakness when I play my planars with hybrid tube amps. They play best with solid-state. I knew these types of amps radiate heat but whoa it is a space heater. It is too hot to handle on the sides and the tubes are cookin'! Maybe an aluminum casing could do better as a heat sink? I'll need to re-arrange my desk for space and ventilation. It'll be good for the winter season to warm a room :)"