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Fostex HP-P1 VS Gen5.5 imod + RSA SR-71B balanced output - Now with Fostex HP-P1 Review Page 2

post #1 of 55
Thread Starter 

Hi guys,


So what are the differences? I am primarily using my Shure SE535LTDs. I have a Fostex HP-P1 on it's way to me Tuesday and I also have a Gen5.5 DIYMod coming but don't have access to a SR-71B to try it out. I will end up either keeping the Fostex or sell/swap it in for a SR-71B. I do have a Tomahawk but not sure if Tomahawk can match SR-71B in balanced output sound quality wise? Reason I ask is no matter how good this Fostex HP-P1 is, I honestly LOVE my Tomahawk's sound to bits so I can't help wonder what the SR-71B has to offer. I also may go with some high end headphones later on such as HS650's and would love to try balanced output.


So basically we're talking


1) Ipod 5.5gen Wolfson WM8758 16bit/44Khz, amp bypassed DIYMod style, DIYMod LOD into the phase splitter in the SR-71B, quad mono amp into balanced output custom cables to Shures


2) Ipod 6th or 7th gen Cirrus DAC chip into Fostex's 32-bit DAC (AKM4480) and inbuilt amp to single ended output to Shures


I know there's a lot of info on the CLAS vs Fostex debate, but I cannot bring myself to carry 3 devices so I think it's out of the question. Besides I wonder how much better a separate DAC is compared to a DIYMod with Wolfson DAC? Doesn't the CLAS have a Wolfson DAC chip too? Surely it can't be leaps and bounds better than the difference between a single and balanced output? But I digress...


I've basically done a google search and read the first 3 pages of results and have not found anything conclusive other than what member EvolutionX has to say about it here: http://www.head-fi.org/t/577387/clas-protector-or-fostex-hpp1-for-jh13s


ALSO: is there any hissing on the HP-P1 with sensitive IEMs? I guess I will find this out on Tuesday


Any additional info would be great help!





Edited by Lillee - 2/23/12 at 4:37pm
post #2 of 55

Hi Lillee,


I don't have a DIYMod iPod so I cannot comment on how it will pair with the HP-P1.   I have sold my CLAS since getting the HP-P1 as I find the DAC section to be slightly better.   The USB charging capability of Fostex HP-P1 also enables me to charge it while next to my laptop as well as utilizing portable chargers for mobile devices.   So far I find the combo of iPod Touch 5G + HP-P1 + SR-71B to be very good with all my iems (JH-16pro, K3003, CK100pro), as well as able to drive my LCD-2 with ease.   If i am on the road, I have the choice to just carry the HP-P1 without the added weight of SR-71B, and most recently I got my Headstage 4G, which add almost nothing to a new combo of HP-P1 + 4G.     I am really enjoying the HP-P1 combo and it also allows me to share my music with a friend with 2 separate output when combine with an amp.   


I have not done a full balance set-up (balance-in from digital source) with the SR-71B, just recabled my JH-16pro and LCD-2 with protector-type input and the sound has improved.    I am still waiting for RSA to come out with their balanced DAC module to really go the full balance way.  


The SR-71B is really a very good amp.  I have sold all my other amps and just keep the 71B to wait for RSA's new balanced DAC module to experience full balanced sound. In the meantime, I am happy with the HP-P1 combo and please be patient with your burning in of the HP-P1 amp section as it does get better after 200hrs.  


Enjoy your music when your HP-P1 arrives......

post #3 of 55


post #4 of 55
Thread Starter 

Hi Evolutionx,

Thanks for the reply! 


Curious that you choose to use the SR-71B amp instead of the built in amp in the Fostex. Is the SQ and/or balanced output worth the extra $$$ for an addition SR-71B amp? As in would you recommend this for those who have not already got an SR-71B? If you did not have the SR-71B would the HP-P1 amp section satisfy your IEM needs?


For me I think carrying 3 items still is too much, plus the added expense of another amp.


I will try these four combinations and see if I get a clear winner:

1) HP-P1 on it's own

2) HP-P1 line out to Tomahawk (bypass HP-P1 amp section)

3) Imod to Tomahawk

4) Imod to HP-P1 Line in (bypass DAC) to see how the amp section does on it's own


Scenario 3 or 4 is pretty good or as good as the HP-P1 DAC (doubtful) then I will know my answer because undoubtedly the SR-71B will be superior to the Tomahawk (?).


I am coming to Singapore in May, maybe we can test the Imod on your SR-71B for the definitive test! L3000.gif

Edited by Lillee - 2/19/12 at 5:33pm
post #5 of 55

Hi Lillee,


You are welcome.


I went thru a few amps (ALO RX MK2, Continental, Ibasso amps, SR-71B) when I was using the CLAS + iPhone 4 combo, and so I did not intentionally buy the SR-71B to pair with HP-P1.    HP-P1 on its own is good enough, especially after burning in and I really do not see the need to pair with SR-71B to enjoy it.   Some iems do not benefit as much from the additional SR-71B amp section, especially without re-cabled to protector type balanced cable.    Considering the costs to get SR-71B plus the recabling, i would say it may be better to use the money to upgrade your iem cable, or LOD cables or just buy another iem.   Plus the weight issue, portability and battery life, etc.  I mainly use my portables at home so I do experiment with different combos with all my iems, which is part of the fun of head-fi.


Like I say, the SR-71B is a very good amp and I am keeping it in case there is a better CLAS or new balanced module from RSA which bring the sound to another level.   In case I am not available in May, you can actually try all these amps at Jaben Singapore.   They do carry RSA amps and many other interesting stuffs.    Cheers.



post #6 of 55
Thread Starter 

Thanks Evolutionx!


Extremely helpful and it satisfies my curiosity with the SR-71B. Yes, as you say if Ray Samuel releases a balanced DAC of some sort in the future, I will definitely have to sell up and upgrade. I really really like the RSA sound and hence why I was curious about how much better SR-71B would be and you've answered that.


I doubt that the iMod can match the HP-P1 DAC section especially since the the HP-P1 outperforms the CLAS DAC as you have indicated. The HP-P1 will arrive tomorrow so if the sound is as great as you and Mike from Headfonia describes it to be, then I've found what I am looking for!


Now I cannot decide if I want to let the Tomahawk go or not redface.gif I like the RSA sound alot and this Tomahawk is a little gem.

Thanks for the info on Jaben, I will definitely have to visit them!

post #7 of 55

Lillie, of course, the Tomahawk is at least 5 to 6 generations old in the RSA line of portable amps.  Nothing wrong with it , it is still a very nice amp.  It's just that Ray, in my opinion, has been able to raise the bar on the sound with each new generation including the Predation, SR71a, Mustang, Shadow, Protector, and the last one being the SR71b.  I have own all of them except for the Shadow which sound very similar to the mustang.  I can tell you that I thought the SR71b has a much bigger sound than all the other RSA amps in balance mode while maintaining the RSA house sound.  So may be down the road you may want to take a look at it.  I think the CLAS can clearly beat the 5.5 gen Imod hands down.  You really should search this forum instead of using google search.  There have been a lot of information on all those devices you listed.

post #8 of 55
Thread Starter 

Yeah I have been looking but there's nothing with direct comparison, esp when it comes to iMod info. There is too much information (how to build one, what's the best capacitor to use) but there's not much out there that says yes, this is as good as "X", and if there are most of it is from 2006...


Thanks for the info on the RSA line, I thought as much but again noone out there has actually said what you just said. 


It's like reading a whole library of books just to find out a snippet of information which can be simply answered by 1 post from someone... and after reading the library of posts, you get even more confused (not all ears are the same, opinions differ, they are using different headphones than is relevant for my situation etc. Too many variables)


Thanks for taking the time to write, I think I have an idea on what I need to do.

Edited by Lillee - 2/19/12 at 7:29pm
post #9 of 55

There has been a few impressions comparing the CLAS to the Imod before the CLAS Solo was release.  You can go to the Solo thread and read about that info.  The long and short of it was that the Solo was clearly better than the Imod because first of its great master clock that reclock all incoming signals via USB asynch transmission, and second, because of the refernce wolfson dac that was used in the Solo, whereas the imod was only able to bypass the amp and still using the ipod dac.  Well, it is especially true that if you have plan down the road to use fullsize headphone, a more powerful amp is desirable to pair with the the Solo.  Good luck with your journey.

post #10 of 55
Thread Starter 

Thanks for the note about the CLAS v Imod info in the CLAS thread. I have been browsing for the last 30 mins and have not read anything definitive yet, just a bunch of people arguing bla bla or cables bla bla... almost given up... only on page 15 out of 60 redface.gif

post #11 of 55


I have a D7000 and a SR71A fed by iPhone 3gs or sony PCM-M10

now I am looking for a source or better amp with tight budget.

I heard that d7k need a better source than amp?

few upgrade choice now

1. sell SR71A get an HP-P1 (the PO can drive D7000?)

2. sell SR71A get an SR71B (will be a lot of retermination job to do...)(huge upgrade from 71A?)

3. sell SR71A get an DX100 (good choice because my files are mostly ALAC)


or 4. Use iPad as source and get DACport(said more powerful than most portable amp!?)

any suggestion?

post #12 of 55
Thread Starter 

I think your weakest link is your source, so either option 1 or 3 will improve your sound quality dramatically more than option 2.


There is an option 5: Keep SR-71A and buy a CLAS to decode your iPhone 3GS



post #13 of 55

thx Lillee

option 5 is good

now i am seeing a L3 FS now

Very Powerful amp right?

sony M10/iPhone 3gs -> L3 good for D7000?


post #14 of 55
Thread Starter 

I have read good things about the L3, but to be honest I prefer the RSA amps for their sound. 


Correct me if I'm wrong but aren't the AH-D7000 only 25ohm? RSA SR-71A should be more than enough to drive them no? Why are you wanting more power? If you get SR-71B and recable the D7000 with balanced cable volume will double.


I think you are better off to sort out your source and get the CLAS for overall performance boost, there are some now for sale, I saw one not too long ago for ~$350, bargain. The iphone 3GS is not the best of the iDevices for sound quality, or so I've read. I feel my iPhone 4S is still not good enough and apparently it is better than 3GS. (iMod > 5.5gen ipod, > 6/7gen ipod, iphone 4S, iPad2 > iphone 4 > Iphone 3GS. This is what I have read, not heard for myself).


Or you can trade SR-71A in for a Fostex HP-P1...

post #15 of 55

The L3 doesn't sound good with just an iPhone as a source IMO.

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