Can I hook up a headphone amp to my integrated?


I am interested in getting some nice headphones.  I currently have a Line Magnetic 518i integrated amp.  As far as I know it has 3 line in inputs which now has my cd player in one, my phono preamp in one, with one remaining.  It also has 1 preamp line out.  The amp has no headphone input?  I mostly listen to vinyl (90%), and sometimes cds as well.  I would like to get a nice headphone amp and hook it up to the LM so I can listen while playing records and cds.  Can I do this, and how would I hook it up?  Can I just hook it up to the remaining line in input?  I would appreciate any help I can get on this....I'm a bit confused if this will work, and if not, how can I go about getting a headphone amp working so I can begin to listen to headphones again?  Thank you all!
ekimg
Thanks Al. I didn't realize the GS-X was $2800. Saw $699 but that was only for 1/4?  Odd way to advertise. Would you do me a favor?  Can you look at the specs for the Woo Audio WA-2 and WA-22?  Those seem to also be preamps with headphone output and 4 line in inputs and cheaper than HeadAmp. Wondering your thoughts on those.  
Both the WA2 and the WA22 have very high 100K input impedances, so in that respect they would be good candidates for approaches 3 and 4 that I had defined. As you’ve most likely seen, the WA2 also provides switching among multiple unbalanced sources, so it would be suitable for approach 4 (no switchbox). I’m not sure that the WA22 would be suitable for approach 4, because it’s not clear if the selection it provides between its unbalanced input and its balanced input keeps those inputs fully independent (i.e., conceivably it may connect the signal on the RCA input directly to one of the two signal pins on the XLR connector, and just ground the other signal pin on the XLR connector when the RCA input is selected. Meaning that the unit may have been designed with the expectation that only one of the inputs would be connected).

Also, you would not be taking full advantage of the WA22’s balanced configuration, since your sources just provide unbalanced outputs. Unless, that is, you used a suitably chosen Jensen transformer (approximately $300) to convert the output of one of your sources (presumably phono) to a true balanced signal pair.

The one slight reservation I have about the WA2 is that the specs in its manual indicate that its power capability into 120 ohms (that being close to the 110 ohm impedance of the LCD-3) is 550 mw (0.55 watts), which falls short of the 1 to 4 watt rating that is stated as being "optimal" for the LCD-3. Although that isn’t a big shortfall, as 550 mw amounts to only about 2.6 db less than 1 watt. But it could conceivably be an issue on material having particularly wide dynamic range, such as some well engineered classical symphonic recordings. The WA22 is fine in that respect, btw (1600 mw into 120 ohms).

Hope that helps. Regards,
-- Al

Thank you Al....you've helped me understand a lot more.  I sent an email to Woo Audio asking their opinion about using LCD-3s with their WA2.  That seems to be a good possibility as long as it is enough.

Someone at work told me I could get a splitter and put on my phono stage output and run one set of interconnects to the integrated amp, and another to a headphone amp.  Sounds like that might work, but not sure how much that might degrade the overall sound?

Thanks again, your explanations have been invaluable in helping me understand the possibilities.

Mike

Someone at work told me I could get a splitter and put on my phono stage output and run one set of interconnects to the integrated amp, and another to a headphone amp. Sounds like that might work, but not sure how much that might degrade the overall sound?
Yes, Mike, that was my approach no. 4, with splitters on the outputs of both the CD player and the phono stage. Given that both of those components have low output impedances, and given that both your integrated amp and the WA2 have very high input impedances, and given that the lengths of the cables that would be involved are not unusually long, I suspect it won’t degrade the sound at all.

My belief has long been that the bad rap splitters and y-adapters sometimes seem to get is not due to the splitters or y-adapters themselves, but in most cases to impedance issues and cable driving issues. In other words, to the inability of the component whose output is being split to drive both sets of cables and both destination components with good results. Neither of those factors will be a problem in this case.

Also, I would recommend this particular splitter.

Good luck. Regards,
-- Al


Hi Al…yes that is your number 4 approach.  I will either do that and get a headphone amp that has two inputs; or get one with the pre out and hook it into my amps pre in.  I talked to my LM 518 amp dealer and he didn't see any problem with either approach (he probably liked the pre amp approach a little better and didn't think it would degrade the internal pre amp any).  I mentioned above that I emailed Woo Audio.  They suggested the WA6-SE or WA22 over the WA2, didn't really give a reason.  Suspect it was related to power.  They also said they could add a pre out to either one if I wanted.  So right now I'm leaning toward the WA6-SE with or without the pre.  It has two inputs so I can just use the splitters you suggested above, or add the pre out.  Anyway, thought you might be interested in their response.  Before you responded I was pretty much in the dark on this, and now feel I have a pretty good understanding thanks to your feedback…thank you!

But let me ask….why is it that you can't just hook up a headphone amplifier to the line in inputs on the integrated, like you do a phono amp?  Just curious :)