[schmalgausen]

Many preamps have direct line-out without voluming. I would use such out with O2 volume, because I believe onboard resistor matches with input imperdance of O2. 

 

[diamondears]

Many preamps have direct line-out without voluming. I would use such out with O2 volume, because I believe onboard resistor matches with input imperdance of O2. 

Yes, I know that. I use the Tape Out of the pre-amp. But since I can't use the pre-amp's volume control and remote control anyway, I just connect my DACs line out to the O2, and use O2's volume.

What I wish I could do is use my pre-amp's volume and REMOTE CONTROL. If I do this, and just max out the O2's volume, this would increase the O2's output impedance? By how much?

 

[WilliamLeonhart]

A question. I have a ODAC board connected directly onto the O2 board (DIY). When I use the line-out of the ODAC (to connect to other amp or to low-impedance IEM), I've found that the sound is considerably worsened. The other amps are pretty ok (Fiio E12K and Little Dot I+ w/ 6CQ6 tubes), and the in-ear that I used were Grado iGi and Sony STH30. 
 
The strange thing is when I use the line out of the O2, everything is fine. I don't know why this happen. Is it that when I connect 2 boards (O2 and ODAC together), the output signal of the ODAC onto the independent line-out is worsened somehow?

 

[diamondears]

A question. I have a ODAC board connected directly onto the O2 board (DIY). When I use the line-out of the ODAC (to connect to other amp or to low-impedance IEM), I've found that the sound is considerably worsened. The other amps are pretty ok (Fiio E12K and Little Dot I+ w/ 6CQ6 tubes), and the in-ear that I used were Grado iGi and Sony STH30. 

The strange thing is when I use the line out of the O2, everything is fine. I don't know why this happen. Is it that when I connect 2 boards (O2 and ODAC together), the output signal of the ODAC onto the independent line-out is worsened somehow?

I think you're just experiencing how good the O2 is. Without the O2, other stuff you do/use just sounds bad...

 

[castleofargh]

a DAC into an IEM is a bad move, plain and simple. the DAC is expecting an easy job going into several Kohm, not feeling like it is short circuiting into an IEM. plus you have to set volume digitally which has limits before you start crushing the music.
 
for the rest I don't know.

 

[diamondears]

There's a reason why we need amplifiers. A DAC or CD player are never meant and designed to amplify. However, if the line outs are balanced, they can be used as good headphone outs, based on what I've read.

 

[saxon48]

There's no harm in keeping the O2+ODAC plugged into power all the time, right?

 

[castleofargh]

  There's no harm in keeping the O2+ODAC plugged into power all the time, right?

I use it mostly at night as I go to bed, put on the headphone, set the computer to turn off at the end of the movie, and often turn myself OFF to sleep long before the computer ^_^. so in effect the O2 is turned ON all night most nights. doing so for more than a year now, nothing exploded yet

.
so I would guess it's pretty safe.

 

[zowki]

This is a question for people who have had the O2 for more than a year. I could never bear to use an O2 for long because I found the volume knob too stiff. Does using it for a year or more cause the volume knob to loosen and turn more smoothly? In comparison, my Leckerton UHA-6S MKII has a much smoother volume knob.
 
Edit:
If it helps, the O2s I've used are made by JDS and Mayflower. Perhaps other manufacturers could improve on this?

 

[Xenophon]

Strange, I own one made by Epiphany Acoustics in the UK, never had a problem with the volume knob, just smooth operation at what I consider a normal (light) level of mechanical resistance. If it hasn't broken in in a year of regular use, it never will. Send them a mail or if the warranty has lapsed, take it apart and check it out to see if you can solve tge issue yourself.

 

[Peti]

Does anyone know what is the default gain settings on the mayflower O2/Odac?

 

[Dark_wizzie]

  Does anyone know what is the default gain settings on the mayflower O2/Odac?

According to Mayflowerelectronics' Ebay listing:

 This amp will drive any headphones from 16ohm to 600 ohm headphones via the switchable gain button which comes as standard with 2x and 6.5x gain settings.

Doesn't mean there's no chance to ask for different gain, that's just the default.

 

[Xenophon]

Yes but what they don't say is that with 6.5x gain, distortion increases seriously at higher volume levels.  And I'd change 'will drive any headphones from 16 to 600 ohm' into 'will drive most headphones'.  Not to detract from the good price/quality ratio but it's not the end-all of amplification.

 

[Solrighal]

This might be useful. Following advice from a serial poster in this thread I've been using my O2 connected to my Marantz PM6004 integrated stereo amp and from there out to my Dali Zensor 1's. The sound is excellent. The O2 volume control is set mid-way and my Marantz volume control roughly the same. It's perhaps worth noting that my O2 has custom gains of 1x/3x (chosen after taking more advice from another poster here). I only use 1x gain.

 

[Xenophon]

I was just about to ask why you're daisy chaining amps but then I realised you were talking about listening to speakers.  I should get myself an ODAC with RCA out, currently listening to my HE-6 on the headphone out of my Pioneer SX-1980 (about 20 WPC into 50 Ohm) but all I've got laying about here to connect it to my PC is a FiiO F17/E09K combo.  Your gain settings on the ODAC are -imo- optimal to drive most cans with good volume control/sound quality.
 
If you'd like to experiment with speaker emulations via headphones, check out the 'Out of your head' thread here.  It's not perfect but some of the virtualizations REALLY make it sound like I'm sitting in a concert hall.