Is this to match the output voltage for the power amp? This I concede may necessitate a Preamp, in which case its quality is important.
Otherwise extra cables, circuits and power supplies must be detrimental in my view. But I'm open to listening, so perhaps it's better if I rephrase my post.
The OP may like to try a DAC, perhaps his current one, without the Preamp in the chain. Carefully of course as software can easily send out full volume which could damage the speakers.
I have, a few days ago, received a Cambridge Dacmagic to use while my Hugo TT is away being serviced. I overlooked the lack of Preamp and consequently am using software to control volume. I am astonished at how good the Dacmagic sounds, and this alongside my Qutest and Brooklyn. But do heed the warning. I do fear I am due an eviction notice from my neighbours. Speakers, thankfully survived.