I use an NAD 3155 from the early 80s as a home headphone amp. It sounds great. It can drive my stats and all of my headphones that have a TRS plug, including an electret. If it can drive an electret from the headphone out without clipping, it's got plenty of guts to drive any headphone. I doubt that a lot of dedicated headphone amps can drive an electret. As for switching sources, it has 4 line ins and a phono stage. The only thing I don't like about it is the tone controls don't effect the headphone jack.
Now I have a Sennheiser HD565 feeded from the headphone jack of a NAD 3240PE. I didn´t compare it to other (integrated od dedicated) amps.
Scompton, I like what you wrote about the NAD3155 (which I wanted to buy just after it went off market, I got the 3240 instead). Does the 3155 just use a resistor between main (speakers) out and phones jack (like the 3240)? Or does it have a dedicated circuit.
Do you think I should be satisfied with my 3240? Or would a cheap dedicated headphones amp for few hundreds of Euros (like Pro-Ject) increase sound quality?
Thanks for giving your opinion!