I'm using nos '56 rca 5r4gy for rectifier, nos tele e88cc in the driver position which I find is the most important tube for sound change and nos tele 7dj8's for the other two spots. I've also enjoy nos ediswan 6922, and nos mullard 6922 in all 3 positions. Tele e88cc is my favorite. In my system it does what you ask.

JD

For my CSP2+ (&CSP3),

I have the following tubes in place.

1x Input tube : Amperex Pinched Waist 6922
Reason, Amperex USA tubes have warm mids, tight bass and a sweet treble. A normal Amperex 6922 is more cost effective and will do an equally great job here too.

2x Driver Output: 2x Siemens E288CC
The E288CC creates an immense and immersive soundstage.
It counteracts the only weakness of Amperex tubes, which is a slightly narrower soundstage.
The mids from the E288CC are also warm.
It has the sonic clarity of a Siemens CCa.

1x Rectifier: Brimar 5R4GY "D" Getter
Reason: This British rectifier creates nice warm mids which have a hypnotic presence.
Cheaper alternative would be a Philips 5R4GYS sold by Upscale Audio.

As usual YMMV, I'm using pure silver interconnects and speaker cables so I always favour the use of warm tubes to tame the naturally bright sounding solid state DACs.

I've been doing some system tube-rolling lately.

In the CSP2+ I always come back to the same combination that gives me just what shootingstar talks about: warm, dynamic sound with tight bass.

For me it's a 'forties RCA 5Y3GT, three 6N1P. I have been trying an Acturus 5Y3GT that is pretty old as I have had amazing success with Arcturus OA3 regulators, but it is just too inaccurate, at least so far. These tubes in this CSP2+ with the Jupiter caps . . . well, this is just the best preamp I've had.