The HD600/HD650 and HD800 have very similar impedance bumps so the effect will be the same.
Perhaps it mates well with DT880's when you find them lacking in the bass ?
These will become more 'bathtub shaped' with boosted bass and upper treble
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Anyway when considering this device (or the bakoon) I would check innerfidelity's plots and have a look at the impedance plots of the headphone(s) you want to use with it.
http://www.innerfidelity.com/headphone-data-sheet-downloadsA massive 'bump' in any parts will emphasize that part of the frequency range.
