If you are upgrading to a new dac.... why don't you get one with the interface you want? The converters are a stop gap solution. I also have a Hag USB... I debate the merit of an upgrade to an asynch converter versus a new dac with an asynch USB built in. I don't hear a consensus of advice on this issue though. Right now.. I lean to a new DAC when the budget will allow.
USB to SPDIF Converters
There are many on the market now.I have a Hag USB .I would like to hear your experiences with these devices.I would like to upgrade soon,to include Hi Rez downloads ,which means getting a different DAC and converter .