[Sonic Defender]

  It's a KR-5150--40 watts per channel on the speakers, drives my Energy RC-10 as loud as I can stand them at about 30% volume (400i are at about 45% before they get unlistenable).  The lamps are all blown, so it needs to be opened up soon anyway, would be a good excuse to swap out the capacitors.

That is a sweet looking classic for sure. There are many threads about it on audiokarma so if you are interested in getting it into tip-top shape, there is no better place on the Internet that I have heard about. Tons of DIY experts, service technicians, audio nuts, you name it, they're all there.

 

[Modular]

Thanks.  That sounds pretty interesting, but maybe a more involved option than I'm up for right now (and I'm not at the point with this hobby where I want to drop significant $$$ on cables--seems like it would be better spent elsewhere).  Would be a cool DIY project if I had the chops...but also seems like it has the potential to damage the cans if done wrong, yeah?

I still have the manual for the Kenwood (passed down from my father--it's been thoroughly cleaned inside, but haven't replaced the capacitors since I received it).  The manual is crazy detailed on the specs, but unfortunately, nothing on the rating for the headphone jack. 

From what I have read, many of those old receivers actually use the speaker output to drive the headphone jack. They couple the speaker out with resistors to limit power. Might be worth looking or asking on audiokarma to see if someone can verify.

 

[Sonic Defender]

From what I have read, many of those old receivers actually use the speaker output to drive the headphone jack. They couple the speaker out with resistors to limit power. Might be worth looking or asking on audiokarma to see if someone can verify.

Yes, that is always how to the best of my knowledge. I don't think anybody was building into them dedicated headphone sections. Maybe on some upper-tier older offerings?

 

[olek]

Yes, headphone jack is powered from 'speakers out' voltage divider on those old amps. I have myself Kenwood KA-6000 amp (actually, 2 of them), and while it is pretty good, it can't hold a candle to Gustard H10 in driving headphones. No, it is not recapped, and maybe its potential is not realized, but I have recapped some other good gear from that time, and it still does not compare to good purpose-built headphone amp like H10 or Crack.
 
In a pinch, vintage amp will do OK as headphone amp, but it is usually better suited for high impedance phones, like hd600 or even better dt880/600; not 400i.
 
I had better experience with vintage pre-amps with headphone out, like NAD 1020 and Hafler 915; they have separate, dedicated headphones circuits, as simple as they are. Actually, they both drive Q701 the best for some strange wicked reason, totally obliterating dedicated headphone amps competition; they do well with T70/hd600, and not exactly great with 400i, but still better than old integrated amps.
 
That was my personal experience for what it is worth. Likely other people had different experience.

 

[automaton]

  That is a sweet looking classic for sure. There are many threads about it on audiokarma so if you are interested in getting it into tip-top shape, there is no better place on the Internet that I have heard about. Tons of DIY experts, service technicians, audio nuts, you name it, they're all there.

Thanks, I'll definitely look into that when I replace the bulbs. I am really pleased with the way the DAC improved the sound out of the RC-10, not a night-and-day difference, but reminded me why I keep the Kenwood around.

 

[automaton]

  Yes, headphone jack is powered from 'speakers out' voltage divider on those old amps. I have myself Kenwood KA-6000 amp (actually, 2 of them), and while it is pretty good, it can't hold a candle to Gustard H10 in driving headphones. No, it is not recapped, and maybe its potential is not realized, but I have recapped some other good gear from that time, and it still does not compare to good purpose-built headphone amp like H10 or Crack.
 
In a pinch, vintage amp will do OK as headphone amp, but it is usually better suited for high impedance phones, like hd600 or even better dt880/600; not 400i.
 
I had better experience with vintage pre-amps with headphone out, like NAD 1020 and Hafler 915; they have separate, dedicated headphones circuits, as simple as they are. Actually, they both drive Q701 the best for some strange wicked reason, totally obliterating dedicated headphone amps competition; they do well with T70/hd600, and not exactly great with 400i, but still better than old integrated amps.
 
That was my personal experience for what it is worth. Likely other people had different experience.

Hmm, that's definitely interesting...haven't had anything higher end to test it against.  Right now the bar the Kenwood has to clear is the SD793ii, not terribly high.
 
I am A/B'ing with the SMSL, and the differences are subtle but there.  Might just be my ears, but the treble seems a little spiky at higher volumes from both sources (one of the reasons I went to the 400i from the 400, hoping the treble would not be quite as harsh), and I suspect that just uneven power from the amps leading me to push the volume higher than I should need to.  

 

[iScream]

Kenwood's got to stay--that's what pushes my speakers! 43 years old and I'm not ready to retire it yet...

 
The Asgard 2 I just got has RCA out.  So I'm running my Modi 2 Uber DAC straight to the Asgard, then interconnects from the headphone amp to my stereo amp to drive my tower speakers.
 
The volume control on the Asgard works for the RCA outputs so it makes a really pure and clean stereo preamp.  Not that you would care about the volume control if you feed the output into your Kenwood receiver.
 
My old HTD speakers sound so good like this that I've got a Crown pro-amp coming to drive a couple new sub-woofers I'm going to build to go with them.
 
-Chris

 

[fjrabon]

been rocking with the EF2C today on the HE400i.  Rolled the tubes to Voshkod 6ZH1P.  It's really a great hybrid amp, especially with the HE400i.  Punchy as all get out, very clean.  The built in DAC is complete garbage though.  But it's not a bad deal at all as an amp only.  And it is a winner in the looks department.  I neglect the EF2C a lot, in favor of the m9XX (and recently the review unit Mojo I've had), but set up correctly, it's a highly recommended pairing with the HE400i.  I also have the Mullards 8100s but to me they're too dark for the HE400i.  However, if you're one of the people that wants to tame the HE400i's treble, the EF2C + Mullards may be the way to go.  But to me, these Voshkods really kick out the jams, punchy as all get out.  
 
Had briefly tried the EF2A, but the volume knob was total garbage, and I'm happy to say that they fixed that here, the volume knob is great.
 

 

[Sonic Defender]

This may be a completely mistaken idea, so feel free to correct me if I'm wrong, but the idea that tubes age I think really puts me off from getting another tube amp. My thinking is that as the tubes age, there would logically be a degradation of sound quality. Is this at all correct or as they fade does the quality of their output remain stable? I think that with people having to buy older, long out of production tubes (although I assume there are companies producing tubes for the audiophile consumer) you would wonder how used they were. I know the better vendors test the tubes, but still, aren't tubes inherently variable in this sense? Curious what a tube-head thinks about this.

 

[DavidA]

  This may be a completely mistaken idea, so feel free to correct me if I'm wrong, but the idea that tubes age I think really puts me off from getting another tube amp. My thinking is that as the tubes age, there would logically be a degradation of sound quality. Is this at all correct or as they fade does the quality of their output remain stable? I think that with people having to buy older, long out of production tubes (although I assume there are companies producing tubes for the audiophile consumer) you would wonder how used they were. I know the better vendors test the tubes, but still, aren't tubes inherently variable in this sense? Curious what a tube-head thinks about this.

From my limited experience the sound starts to degrade, loss of dynamics is what I noticed in the one tube that I had go bad/die on me.  The tube was noted as being used when I got it but the actual time that they had been in use was unknown.  It lasted about 5,000-6,200hours from my estimates, about 2 years at 8-10hrs per day.  I have 2 tubes that have over 6,000 hours on them if my rough estimate is in the ball park, they still sound good and are currently in my Lyr2.
There are some re-issue tubes out there, not bad for the price.  I guess that's why many buy 2-3 sets of tubes if they like them.

 

[Headphone4Life]

been rocking with the EF2C today on the HE400i.  Rolled the tubes to Voshkod 6ZH1P.  It's really a great hybrid amp, especially with the HE400i.  Punchy as all get out, very clean.  The built in DAC is complete garbage though.  But it's not a bad deal at all as an amp only.  And it is a winner in the looks department.  I neglect the EF2C a lot, in favor of the m9XX (and recently the review unit Mojo I've had), but set up correctly, it's a highly recommended pairing with the HE400i.  I also have the Mullards 8100s but to me they're too dark for the HE400i.  However, if you're one of the people that wants to tame the HE400i's treble, the EF2C + Mullards may be the way to go.  But to me, these Voshkods really kick out the jams, punchy as all get out.  

Had briefly tried the EF2A, but the volume knob was total garbage, and I'm happy to say that they fixed that here, the volume knob is great.

Been thinking of getting one for a while now because it seems to be good value for money as an amp. I think I might just make it an early birthday present to myself. I know the 400i will sound good but my darker Sony Z7 is a different story, haven't liked it much out of the 2 hybrid amps I have.

 

[James Myers]

  been rocking with the EF2C today on the HE400i.  Rolled the tubes to Voshkod 6ZH1P.  It's really a great hybrid amp, especially with the HE400i.  Punchy as all get out, very clean.  The built in DAC is complete garbage though.  But it's not a bad deal at all as an amp only.  And it is a winner in the looks department.  I neglect the EF2C a lot, in favor of the m9XX (and recently the review unit Mojo I've had), but set up correctly, it's a highly recommended pairing with the HE400i.  I also have the Mullards 8100s but to me they're too dark for the HE400i.  However, if you're one of the people that wants to tame the HE400i's treble, the EF2C + Mullards may be the way to go.  But to me, these Voshkods really kick out the jams, punchy as all get out.  
 
Had briefly tried the EF2A, but the volume knob was total garbage, and I'm happy to say that they fixed that here, the volume knob is great.

Hmmm certainly tempting as I'm someone who loves a dark/warm sound.  I wonder how that stacks up to the APPJ1502A

 

[Socratease]

  The built in DAC is complete garbage though.  

Can you swap it out and put in an ODAC board?

 

[fjrabon]

Can you swap it out and put in an ODAC board?

No, doesn't appear so.

 

[Born2Cuddle]

  been rocking with the EF2C today on the HE400i.  Rolled the tubes to Voshkod 6ZH1P.  It's really a great hybrid amp, especially with the HE400i.  Punchy as all get out, very clean.  The built in DAC is complete garbage though.  But it's not a bad deal at all as an amp only.  And it is a winner in the looks department.  I neglect the EF2C a lot, in favor of the m9XX (and recently the review unit Mojo I've had), but set up correctly, it's a highly recommended pairing with the HE400i.  I also have the Mullards 8100s but to me they're too dark for the HE400i.  However, if you're one of the people that wants to tame the HE400i's treble, the EF2C + Mullards may be the way to go.  But to me, these Voshkods really kick out the jams, punchy as all get out.  
 
Had briefly tried the EF2A, but the volume knob was total garbage, and I'm happy to say that they fixed that here, the volume knob is great.
 

Do the tubes get too hot to tie a string around them?