Audiophilepure

https://www.soundstageultra.com/index.php/equipment-menu/1311-engstroem-arne-integrated-amplifier

I’ll happily vote the Arne in as the most elegant component that’s flowed through my listening room. There. I said it. But the Arne isn’t just a pretty face. It’s fully balanced, from input to output, which is perhaps the most interesting design feature, since you don’t see this type of configuration on other triode tube amps. It’s a pure class-A amplifier, using direct-heated triodes, with zero negative feedback. What further distinguishes the Arne is its direct-coupled driver stage, which connects directly to the power tubes.

The Arne employs two 300B power tubes and two D3A driver tubes per channel. You don’t see many D3A tubes these days. The D3A is a nine-pin miniature frame-grid pentode developed in the 1950s for wideband telecommunications applications. The particular ones in this amp are Siemens NOS types, and I envision Timo Engström purposefully descending a ladder into a well-provisioned cellar containing a steamer trunk full of these little guys. The 300Bs are high-quality tubes from Emission Labs. Engström carries a host of other brands, and you can discuss other options for driver and power tubes with them at the time of purchase.