What do DHT (direct heated triodes) REALLY sound like? Yes we've heard VT25, 45, 2A3, 205d, 300B etc in many an amplifier, enshrouded by driver tubes and output transformers. And we can plainly hear the differences between DHT types in that context, tainted though the sound must be with so many extraneous elements.
The only way to really hear the sound though is to go spud. And what better place to do that than right at the beginning - the linestage. Many will say that the linestage contributes more than the amplifier, so...

UX4 sockets: this would allow 10/10Y/VT25, 26, 45, 71A, 2A3, 801A/VT62, 300B, 101D, 205D if we can design in enough control to supply the variety of filament, and B+ voltages needed. Used spud we'd have a friendly gain structure of between 9 and 18db. Most have lowish anode impedance; no transformer needed as in the range ideally suited for preamp duty. So...OTL it is!

With adjustable CCS for the anode we can control the anode current. Easy done.

Since this is an all-out attempt to hear the real DHT, and all of it, we don't want un-necessary caps in the signal path. So let's go fixed bias, thus avoiding the cathode bypass cap. To make this easy we have our ABS module feeding the grid which can be set with one resistor for the desired operating point.

Power supply: to stay with the theme lets use a DH rectifier tube. We don't want ANY electrolytic caps blowing smog into our sonic landscape so we will let the all film-cap FCUPS module provide the P:USH power we need. This has the added advantage of supplying the bias voltage needed by the ABS and bonus: jumper setting for virtual battery or virtual choke operation. And it is super quiet.

The filament supply also needs to be quiet, be a brick wall to the signal (DHT, remember?) and be adjustable: DIYHFS filament supply just happens to be on our shelf.

Transformer noise will be an issue so let's order a potted (3mm steel) torroid which has the advantage of radiating EMF axially thus avoiding noise in the chassis. Our goal is to do this all on one chassis. We'll mount tx forward, to keep it away from the signal end of the chassis.

We'll need one pair of 2.2uf/250v coupling caps for output and 1 pair 0.1uf on the input grid.

Chassis will be the Projekt Box, also at hand.

Layout will look something like the attached.

Here we go!