The Pass Labs web site has just been updated with information on the new X.5 series. See the following url:
http://www.passlabs.com/products.htm
In particular, the page on the new x600.5 has information on some of the electric design improvements, as well as some photographs:
"**Expected to ship in the first quarter of '05**
The X600.5 is the natural progression of the X600. Changes include improvements to power transformers, paralleled high speed / soft recovery rectifiers, improved AC EMI filters, more paralleled power supply capacitors, increased supply RC filtering, refinements to the front-end input circuits, and the addition of single-ended Class A bias circuits for balanced single-ended Class A at low power levels.
All of these changes bring the X.5 series closer to the sonic signature of the XA series amplifiers.
The X.5 series feature the distinctive front panel meters indicating of the level of current running through the output stages that have long been the visual signature of X amplifiers.
The X600.5 accepts both single-ended and balanced inputs. . ."
The X600.5 should become available early in the new year. It's smaller brothers are already shipping. While we wait for X600.5 to be completed and to start shipping, I love to hear from any new X350.5 owners with their live impressions/findings.
