I had the same experience the first time I listened to my mhdt Havana Balanced DAC. With some experimentation I quickly learned a few things that change my satisfaction dramatically. First, the stock GE 5670 buffer tube sounds bland and perhaps this is a good way to ship mhdt DACs because the stock tube will be forgiving in any system. But better to change it. You'll see in mhdt's literature a long list of alternate tubes to try. I found the Bendix or Tung-Sol 2c51 and the Bendix 6385 to open up and enliven the DAC in a big way.
Next, like many things digital, these mhdt DACs are very sensitive to what they are resting on. My custom racks are solid maple but the Havana Balanced doesn't sound convincing sitting on any surface on its own feet, in my experience. After many trials, Aurios media bearings under it were transformational to the DAC's sound, giving it explosive dynamics where appropriate, beautiful and dense tone, and remarkable definition.
I also found some PCM56K chips to give it further improvements in definition, tone and spatial projection, over the stock J versions. These are cheap.
Last it takes some time to burn-in/break-in. But clearly resting the Havana Balanced on Aurios media bearings was the single most significant improvement. It was transformational even with the stock tubes and chips. I'm pretty sure Herbie's Tenderfeet will also work well for less. Magnetic levitation did not help. Sorbothane made everything worse. Brass cones were the next best resting method to bearings. I think any bearings-based footer is the right way to go with an mhdt DAC.
The Stockholm is the Havana DAC with a 24/192 input receiver. I should add that I haven't yet moved to computer file audio and while I have fiddled with the USB input on my Havana Balanced, my definitive listening as been via SPDIF input from optical disc. What input are you using? I think many mhdt DAC owners find a USB>SPDIF converter, even just a HiFace or mhdt's own, to be preferable to the mhdt USB input natively built into their DACs.
These mhdt DACs can sound beautiful, organic and wonderfully dimensioned. Upgrading internal capacitors can take things further. But out of the box, it takes some effort to put them in their zone.
Phil
