Input impedance matching and Crack

[kevin flynn]

Hi,
New crack amp user (v.s. crack user), exploring best combinations with this amp.  So far, using BD DT770s paired with my Dynaco PAS 3 pre, or custom tube line and phono stage.  Initially, didn't care at all for the sound of the headphone amp paired with either preamp set up... waaay to forward to the point of brittle. 

So on a whim, I connected my tubed CDP and phono stages directly to the headphone amp....VOILA, now  we're talkin'...  treble steps back, midrange emerges and bass (never a problem) is sounding good. 

So, though I'm not sure of all the technicalities (?) now I'm wondering if the output impedance of the tubed pre's are a bit high for the 100 ohm impedance of the amp.  In any case the amp seems to be a much better combination with the separates themselves.

Other opinions/experiences?

K. 

[Doc B.]

Crack has a 100K ohm input impedance, not 100 ohms. That should be an easy load even for a preamp with a high output impedance. 100 ohms is the output impedance, which is only affected by the headphone load.

The issue could be that your preamp doesn't like the interconnect between it and the Crack. At any rate, Crack has plenty of gain and an attenuator, and really doesn't need a preamp between it and a typical source. So in fact you should now have the best setup from the theoretical viewpoint of less stages creating less coloration.

[kevin flynn]

Um, yeah, oops! 100 "K" ohm. 
Omitted the multiplier in my mail....!

Thanks,

Kevin