As for the initial posed question? I would recommend the Krell Combo you have listed over the Pass combo you have listed. I think a better comparison is the X-1 with the 250.5 or much better yet, the XP-20 or XP-10 with the 250.5. The prior Pass amps (150, 250 etc. . . prior to the .5 versions) are no where near as good as the ,5 versions. This is based on my ownership.
I think the comparions between the Pass XP-20 (or 10) with the Pass 250.5 versus the Krell KCT/FPB300CX is going to come down to a matter of taste more than one being better than the other.
I know two places where you can get a Pass X-10 preamp for about $900 off the list price (one is new and the other is almost new). Neither are mine, but both were offered to me for sale.
I presently have the Krell FPB 300 C (no X) and Wilson W/P 5.1 speakers. I have gone through many preamps and to me this is my toughest component. I am looking for a new preamp at the moment (in the meantime I am running my Krell HTS 7.1 (new from dealer 1.5 years ago, for direct 2-channel operations, this unit uses a preamp based on the KCT and is supposed to be very close (90%) to the KCT, which I did compare at the dealership and agree with - both run balanced vs. with cast) until I find something else. I am surprised by how good the HTS 7.1 does as a preamp (better than many of the dedicated 2-channel preamps I have tried/owned).
Since you have been mighty impressed by what you have heard with the Krell equipment in the past and the Pass is unknown, I would go with the Krell equipment. The sound between the two is not better vs. worse, but a little bit different - a matter of personal preference.
I think the comparions between the Pass XP-20 (or 10) with the Pass 250.5 versus the Krell KCT/FPB300CX is going to come down to a matter of taste more than one being better than the other.
I know two places where you can get a Pass X-10 preamp for about $900 off the list price (one is new and the other is almost new). Neither are mine, but both were offered to me for sale.
I presently have the Krell FPB 300 C (no X) and Wilson W/P 5.1 speakers. I have gone through many preamps and to me this is my toughest component. I am looking for a new preamp at the moment (in the meantime I am running my Krell HTS 7.1 (new from dealer 1.5 years ago, for direct 2-channel operations, this unit uses a preamp based on the KCT and is supposed to be very close (90%) to the KCT, which I did compare at the dealership and agree with - both run balanced vs. with cast) until I find something else. I am surprised by how good the HTS 7.1 does as a preamp (better than many of the dedicated 2-channel preamps I have tried/owned).
Since you have been mighty impressed by what you have heard with the Krell equipment in the past and the Pass is unknown, I would go with the Krell equipment. The sound between the two is not better vs. worse, but a little bit different - a matter of personal preference.