I want make choice between RSA SR-71A and P51! anybody can give me some tips?!
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SR-71A or P51!!!
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- Freeze
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no recharge ability on the sr-71a kinda a hassle. I'm getting a p-51 once i sell or trade my pico slim
- Radio_head
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which headphones do you have?
For something with higher impedance, (like the sennheiser hd600/650, beyerdynamic 770-990,) sr71 would work better. Otherwise go with the p51. I tried them both at ray's house and for lower impedance headphones I actually preferred the p51. And freeze is right, changing batteries on the sr71 is annoying and expensive in the long run, whereas the p51 can be charged.
Edited by Radio_head - 8/3/11 at 8:54am
- Freeze
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p-51 isnt exactly terrible at driving higher impendence. It will still greatly help compared to no amp at the highest gain setting.
The carrying around of batteries. Buying them constantly. The difference in SQ isnt worth the hassle and constant additional cost of buying 9 volt batteries which happen to be like the most expensive ones.
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He can buy a pair of rechargeables...
- Freeze
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Meh I think it still sucks having a completely different unit recharging and switching in and out bleh.
I owned the Hornet M , 71a and the Mustang.
My wife uses the Hornet and I use the 71a.
We both use Senn HD 25-1 II headphones with them.and special cabling
I have a portable charger and a couple xtra charging batteries.
My wifes is rechargeable from the wall.
I dont find it a hassle to replace batteries, 1,2, 3 and your done, put the battery in charger and enjoy the fresh one in the 71a
Inital output for charger and xtra batteries, You wont be buying batteries all the time.
I'm willing to do this, as i like the sound from the 71a over the other two mentioned above.
Incidentally, I use a V Dock, piggy backed, to give it more slam. I remove the V Dock and even use it on my home rig, the RS Raptor.
We also both have Imod Ipods
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The SR71a is definitely one of the highest powered portables on the market. That 18volt 9x2 battery power source really lets the juice loose. It is a nice amp but the battery style just isn't for me. And all i have are sensitive Westone 3 limited edition IEM's. And soon Ultrasone pro 900's which are low impedance full size so they don't need the incredible sr71a power either.
I think the sr71a is only good for people that have 600ohm super power hungry headphones. Even then so there may be other choices that perform just as well with an easier battery system.
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I use the SR71A for the amount of power it provides. I use my se425 and my HD600 and it powers it beautifully. I have a 9v charger that does two pairs. Open the back, grab the freshly charged set of maha 9v and it's quick and does not require much. I just got a DT880 600 ohm last week and I am awaiting for my tube amp this week. I was just curious and plugged it to the SR71A, at hi gain and at 12:00, good detailed sound. At 3:00 it has enough jioce to power the 600 ohm cans. It all depends on what you want. They are both great amps. Sometimes, just go with your gut and what you want. You learn from this. Hope this helps.
- roma101
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Could the P 51 power the HD600 (or DT880/250) adequately? Right now, that's the only amp I have. Does anyone think I should just save up for something like the Stepdance?
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I use the SR71-A with HD600's and is one heck of a simpatico combination -- really a match made in heaven. So, if the HD600's are a key criterion, I highly recommend the SR71. Swapping out batteries is no big deal.. As stated earlier, get 4 Tysonic low-discharge 9V and the charger. With and extra set of batteries to (takes like a minute at most replace) you wind up with really extended play time, which is a big deal to me with long trans-Pacific flights with layovers/connections.
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High impedence cans need voltage. That's a technical requirement, based on ohm's law. If you don't give them enough voltage, the tops of the signal will clip off. At first you'll just lose dynamics (i.e. drum transients), and with more extreme clipping you'll get distortion. Clipping can also cause strain on the amp.
For 250 ohm cans, you need about 3.9 volts. 300 ohm cans need about 4.25 volts. 600 ohm cans need about 8.5 volts. It also depends on sensitivity and how loud you listen, but those are good ballpark figures.
The P-51 is borderline for 250 ohm or 300 ohm cans as far as voltage, but should sound good as long as you don't listen too loud.
- roma101
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I use the SR71-A with HD600's and is one heck of a simpatico combination -- really a match made in heaven. So, if the HD600's are a key criterion, I highly recommend the SR71. Swapping out batteries is no big deal.. As stated earlier, get 4 Tysonic low-discharge 9V and the charger. With and extra set of batteries to (takes like a minute at most replace) you wind up with really extended play time, which is a big deal to me with long trans-Pacific flights with layovers/connections.
Thanks for the input. I'll definitely keep the SR71A in mind down the line as I really want the HD600's in the near future. And I agree, changing batteries is not too much of a hassle, although I'd probably get rechargeable batteries if I got tired of it.

High impedence cans need voltage. That's a technical requirement, based on ohm's law. If you don't give them enough voltage, the tops of the signal will clip off. At first you'll just lose dynamics (i.e. drum transients), and with more extreme clipping you'll get distortion. Clipping can also cause strain on the amp.
For 250 ohm cans, you need about 3.9 volts. 300 ohm cans need about 4.25 volts. 600 ohm cans need about 8.5 volts. It also depends on sensitivity and how loud you listen, but those are good ballpark figures.
The P-51 is borderline for 250 ohm or 300 ohm cans as far as voltage, but should sound good as long as you don't listen too loud.
Very informative and concise response. That's actually exactly the information I needed, and I will definitely take note of it and refer to it when purchasing the next amp/headphone combo. Much appreciated.
Edited by roma101 - 8/28/11 at 5:46pm
I think stepdance can drive those headphones good (I like to use it with D2000-> deep sound stage) , well some of headphones is very picky. Im looking to sell my stepdance, moving on to desktop amp, no more traveling for me. D
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PM me when you decide to sell it or if you are open to trades. I can't guarentee if I'll have the money by then, but I've been interested in the Stepdance for a very long time now.
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