I have had the Pass X2.5 preamp for five months, initially into the Aleph 5 with balanced interconnects and now into the GamuT D-100 Mk. III. This is a wonderful fully balanced SS preamp. It is very quiet, with excellent clarity, smooth, great sound stage and all the other attributes of a great preamp. I think it is near world class at a value price. TAS rates the Pass X1 very highly which I've been told sounds very similar to the X2.5. These preamps are the next generation after the Aleph-P. Ultra Audio reviewed Pass X2.5 on feb. 15, 2003 and compared it with a 14K Rowland design and it was fairly close. Nelson has plenty of info on his preamp at his web site.
