Benchmark DAC1 Pre - anybody heard a mod?


I have a Benchmark DAC1 Pre that I am fairly happy with. I have seen and read several posts from people offering modifications to the DAC1 that apparently increase warmth, resolution and imaging. Does anybody own a modified DAC1 or DAC1 pre that has been modified? What were the modifications, costs and sonic improvements? Your advice will help me decide if this is the right decision for me.

Thanks
beatster
I have an upgraded Zu Audio Bok power cable on my Benchmark, and it basically lowers the noise floor, and provides for a clearer, cleaner presentation which is really cool, so the notes sound like they are more isolated projecting out of a darker background. I'm not using any power conditioning though.

Rich
Richlane - Thank you. It sounds very clear on my system with stock power cable but exact location of notes/instruments is a little fuzzy. I will try conditioner and/or different cables.
I would try an upgraded power cable first, then do power conditioning only if necessary. As stated many times here before, sometimes power conditioners can suck the life out of a system, and then again sometimes they're necessary.

Good Luck!
Thank you all for your suggestions. I took the plunge...bought a MHTD Labs Havana DAC. The Havana is a NOS non-upsampling DAC with a tube buffer. The unit arrived today and I am running it through the analogue inputs of the Benchamrk Pre. So far so good! The DAC still needs to be run in but the 'harshness' of the Benchmark is gone. The sound is 'fuller' and the clarity and resolution of the Benchmark is still there. The bass sounded a little muddled at fist but this is clearting up as well.

I could have possible gotten the same outcome from a tube pre but there are not that many good deals in the Singapore market.

So now I have 2 DACs. Will probably sell the Benchmark in the near future and get a proper pre-amp once the Havana is run in. The question would be tube or solid-state. The journey goes on...
I have just bought the DAC1 USB to replace my XDACV3. The XDAC has a sweeter treble but not quite as much resolution. I agree that the DAC1 does sound a bit tipped up in the high mids and treble. I suspect that some of this is due to the LM4562 output op-amps which do have a pronounced 'presence' but I also feel that the power supply caps are largely responsible. I have some experience with the 4562 op-amps and have found that bypassing with Elna Silmic or Cerafine mosly eliminates the glare and the result is much nicer and sweeter mids and treble. There are also a couple of 5532 op-amps used for I > V from the DAC. The XDAC also used these devices and I ended up substituting them with OPA2134 amd the result was less grain + smoother and sweeter as well as a much fuller bass. I will probably do a full range of mods to the DAC1 USB in the very near future and will report back here.