Full link:
http://www.thevintagesound.com/store/tube-amp-doctor-tonebone-pentode-matched-pair-includes-2-tade-p-392.html?zenid=2c57f1e06bccd7d8b80e1ac6eabf96d8 (Pentode/16W version)
http://www.thevintagesound.com/store/tube-amp-doctor-tonebone-triode-matched-pair-included-tadel84-p-391.html?zenid=2c57f1e06bccd7d8b80e1ac6eabf96d8 (Triode/9W version)
I've not tried these exact ones, but there are others on the market that do the same thing. I've tried THD and Groove Tubes ones. They work well and give you lower headroom and a more compressed EL84-type character.
What they don't do despite some claims is make your amp sound like a Vox, or run in Class A, or make it substantially quieter for bedroom playing - all they do is reduce the headroom at maximum volume and change the tone a bit, the volume at any setting below power-stage overdrive is more or less unaffected. 16W is still LOUD - it's just not quite as deafening as 50, and doesn't have quite as much presence and authority. Even 9W isn't really bedroom volume, and triode mode sounds even more different.
If that sounds like what you want, they're an easy way of getting it. If you want to keep the tone of your amp the same but make it a lot quieter, you need an attenuator instead.
