I would look for a solution before purchasing a pre...
What you describe sounds like the Delius isn't driving the amp too well -- i.e. the dac's output impedance is too high at certain frequencies. This is surprising though... what's the VT100s' input Z? I assume the Delius is 600ohm or less.
Items like the SCE mentioned above by Listener provide a "buffer" service so as to achieve a better transfer (i.e. a lower source impedance to achive better voltage transfer to the load/amps).
A pre would add another stage to yr chain. It would drive yr amps more easily at the expense of some resolution (unless you go for the exotic, i.e. Blowtorch, & the like).
What you describe sounds like the Delius isn't driving the amp too well -- i.e. the dac's output impedance is too high at certain frequencies. This is surprising though... what's the VT100s' input Z? I assume the Delius is 600ohm or less.
Items like the SCE mentioned above by Listener provide a "buffer" service so as to achieve a better transfer (i.e. a lower source impedance to achive better voltage transfer to the load/amps).
A pre would add another stage to yr chain. It would drive yr amps more easily at the expense of some resolution (unless you go for the exotic, i.e. Blowtorch, & the like).