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That MT-604 sounds better when you swap out the china tubes.

Hi output on DO300EX MT-604 I set mine 3/4 most times and always unplug headphones before power off the MT-604 Use the single volume on the DO300EX to adjust the listening volume DO300EX to zero and MT-604 whatever power suits your speakers I just start up my dac first and lower volume then...

I am UK based xlr

It doesn't really matter buy/spend what makes you feel Good is all the same, but for reference I tend to use Visiosound 2 x Male XLR to 2 x Female XLR Balanced Microphone Twin Lead/Audio Patch Cable 0.5m OR WORLDS BEST CABLES when they are in stock. Just plug the xlr to both units and your...

Xduoo MT-604 4.4mm or HansnBy 4-pin XLR Male to 4.4mm image one 4.4mm Male to 3.5mm Female adapter if your headphones are 3.5mm image two

XLR lead to SMSL HO-200 to DO300X 4.4mm/6.35mm Headphone Output for DO300X 4.4mm/6.35mm/4-Pin Balanced XLR for SMSL HO-200

I have two options for you both of which I use for my second system, the Xduoo MT-604 will power the DO300X to a really powerful strong sound, be careful set it half way and turn down the DO300X and them both up slowly because your damage your headphones it is a lot of power, also if you get it...

If you don't already have Xduoo MT-604 Tube grab one, might even be on sale will help the 300EX by getting rid of the only Con noted in review.