Tube preamp topologies and music

If you're saying you have Heresy 4's, you have a lot of options.  The Airtight amps would be a good bet.  Personally I would choose the ATM1.  You don't need more power than that, and IMO the EL34 is a very sweet tube.  Really, 15-30 wpc would be PLENTY of power.  

First of all, I disagree with some of the comments above.  A well-contructed single-ended amp can rock pretty hard with the right speakers.  But the key thing for you is, what kind of speakers do you have?  That's going to determine the amount of power you need, and that in turn will go a long way toward dictating the tube choices.

In all fairness, I thought jasonbourne71's comments were pretty on point overall, and I should have made that clear in my own comment above.

If you have the Dennis Had equipment, why not hook it up and try it? You’ll know quick enough if it works for you or not.

Most single-ended tube amplifiers have relatively high output impedance a) because only one output device is being used and b) because they usually don’t use feedback, which also contributes to higher output impedance and poorer damping factor. Your amp uses multiple devices in parallel, and also most likely a good bit of feedback, both of which greatly reduce the output impedance and increase the damping factor.