My tube headphone amp (from Ebay..."Bravo" 12AU7 brand, although there are various versions out there) from China took a week to get here and cost around forty bucks shipped. The power supply died and they shipped me a new supply free of charge right away. Luckily I have an extra set of outputs on my preamp for it and it all works really well...drives a pair of Grados easily with tons of headroom. I had no idea this thing would be so good and all I added was a supposedly better tube.
A question about preamplifiers and headphones
I have a NAD C162 preamplifier (I also have NAD C272 power amplifier and a NAD CD/SACD M5 player). I wonder if I can purchase Sennheiser HD 598 headphones and plug them into the headphone plug on my preamplifier, or whether I might need to purchase a separate headphone amplifier in order to listen to these headphones. I have received contradictory advice about this matter. I would love not to have to purchase a dedicated headphone amplifier. I mainly listen to classical music in my own living room.