[rgs9200m]

I have used a preamp (a McIntosh C46 and a Rowland) to get remote volume control for my headphone amps
with surprisingly good results.
 
If a tube unit is used in a solid-state setup, it can add some add some tubiness.
(They actually sell tube buffer units; PS Audio I think has these.)
 
And some preamps have bass/treble controls (Macs, Accuphases, Van Alstines.)
And also, you can get some more boost for a headphone amp that may not have enough power.
 
Has anyone tried this?
 

 

[Gazza]

Bad idea; you're just adding more into the signal chain.
 
The best idea would be to have a high quality headphone amp that is a preamp, thus ensuing no signal degradation.

 

[Uncle Erik]

Yes, but I don't feed the preamp out into my headphone amp, for the reasons Gazza states.

However, a tape loop out or record out connected to your headphone amp lets you use the preamp to select sources and gives you the option of running speakers.

 

[rgs9200m]

I do this:
CD-Player --> Preamp --> Headphone Amp --> Phones
 
Works for me in A/B test with no Preamp.