Hmmmm…Tough call depending on what your chain is?.. Voskhod or Mullard are more well “tubey” on the MT-604…Siemens are a tad less “analogue”…so wide tube style then I’d go Mullard easy to source too 
Thanks! I’d be running Singxer SU-1 > Gumby MB > Kinki THR-1 > MT-604. Then something like HE-500 or HD560s, maybe Timeless if I get a balanced cable for it. I miss my LD mk. III! I picked a 604 up for a few quid and thought I’d give it a go.
Thanks for the information, I’ll hunt some Mullards down.
Hello Sirs
They sell me the mt-604 cheaply, but I have many doubts about its balanced connections. Please if you can respond I would appreciate it.
What will happen if I buy an unbalanced xlr to 3.5 adapter for the amplifier output? (could something break?)
Are RCA to XLR connections safe?
I was reading in other forums, the mt-604 is a hybrid. Does this mean I can use the MT-604 with flat drivers?
I appreciate in advance any contribution that helps me clear up my doubts 
Sorry for the delay.
The Hybrid is the tube style, basically the amp is still solid state, but uses a tube pre amp, which is where the hybrid comes from.
The only inputs are 3 pin XLR and the 4.4 balanced on the front.
The outputs are the 4 pin XLR and the 4.4 balanced on the front.
This is only an amp, so you still need a DAC, and preferably balanced, or you defeat the point and should just look at the way cheaper MT-602. The 602 is also just an amp, but is not balanced, and you could use something as cheap an apple DAC and a 3.5mm to RCA cable.
My current setup is a Topping DX1 which is a DAC that only has USB input ( I run my PC into it ), then I run it into the MT-602. They were each under $100 when I bought them. The DX1 gives 560mW solid state, and the MT-602 is 1300mW tube sound.
The good ol balanced / unbalanced question…
I have a fully balanced stack - Topping E50 → L50 - but I want to try out some older headphones as well as my balanced ones.
Is there literally zero safe adapters to use either the 4-pin XLR or the 4.4mm outputs with standard 3.5mm unbalanced headphones? i.e. without tearing apart headphone cables?
If I use a single-ended RCA out → Xduoo’s XLR, can I then safely use a 4-pin XLR or 4.4mm balanced → 3.5mm unbalanced headphones adapter? The topping stack has both balanced and unbalanced ourputs that I can switch between.
i.e. something like cables from the Topping E50’s unbalanced RCA to the Xduoo’s XLR balanced inputs: https://www.amazon.com/Cable-Audio-Amplifier-Microphone-JOLGOO/dp/B07ZVY3R53
And this adapter for some standard 3.5mm headphones to go into the Xduoo’s 4.4mm: Amazon.com
The only other option it would seem is to have two tube amps, one for balanced, one for unbalanced?
You can’t go SE to Balanced but you can go Balanced to SE…I use the 4.4mm out on my DAP to an RCA in and a 4.4mm IEM/HP cable adaptor to 1/4” however this would not work in reverse.
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Apologies - yup, just needed to read up a bit more.
Will start searching for a hybrid tube amp that can do both balanced and unbalanced. Any recommendations?
The general rule of thumb is if an amp has both a SE and Balanced out it will prioritise one over the other quality wise which usually ends up being the balanced one…@WaveTheory do you know of any/have any recs for hybrid tube amps with both SE and Balanced outs? 
How is the MT-604 in 2024? still good or shall i save more and go for the TA26S directly? looking for HD660S2.
Tough call but when I had my HD660s’s I preferred them on an OTL but YMMV.
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indirectly pointing me to go all out on a good OTL hehe will save for TA26S then.
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I think it would work out better for that set but not if you want to drive planar’s
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I am currently out of planar game in headphones. I currently have the HD660S2 and maybe will buy Bokeh this month(if my pocket allows).
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Came across this which appears to haev both balanced and se ins and outs. Sounds meh, yes, but seeing it offmarket for cheap and I’m thinking it might be a good introduction to experiment with. Loxjie P20 - Balanced Hybrid Headphone Amp
I have both a Liquid Platinum and a TA-20 hybrid tube amp and they are both great driving my 660S. Balanced all the way. That said, I do hear that OTL sounds even better. I have been looking at the TA-66, myself.
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Could always have a go at building one …
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re: balanced and single-ended - found this one as well. So few reviews on it though and the power seems to be less than the Loxjie P20:
https://www.amazon.com/Headphone-Amplifier-Balanced-Audio-Headsets/dp/B09LQML7W6
Is Suca Audio and Douk Audio the same thing?
http://sz-sucaaudio.com/audio-VacuumTubeHeadphoneAmplifier.html
Many hybrid tube amps have both balanced and single ended outputs, but as you pointed out the single ended outputs tend to be quite compromised in comparison to the balanced output. @midimid the trick is going to be finding a tube amp that has a balanced output on it but is actually a singled ended amp that has a balanced output as a convenience. Look at the power output specs. The if the rated power output from the single ended output is less than the balanced output, that’s a balanced amp with a single ended output added for convenience but that single ended output will be significantly behind the balanced output sonically.
No, DO NOT just use cables that are XLR at one end and RCA at the other unless the manufacturers of the gear explicitly say you can do so.
No, DO NOT adapt a 4-pin XLR headphone output to a single ended cable.
However, you can adapt a 4.4mm pentaconn balanced headphone output to a single ended headphone connection. Here’s an example. The key is the 5th conductor on the pentaconn can handle the shared ground safely. 4-pin balanced connectors have no way to do that, so you’ll end up connecting the 2 balanced amp circuits together and praying you don’t blow it up.
The xDuoo TA20 Plus is a reasonably priced tube hybrid that has a 4.4mm pentaconn headphone output on it. So maybe check that out.
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This is hard to import Bottlehead, well it is hard to import everything here to my country lol. Customs uncle will enjoy it more than I do.
Last time they got a hold on to my SP2KT, i bought a used unit from hongkong for 1000$, they were asking me 1700$ in customs and import taxes. Had to let go of that device 
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