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Comparison Of Five Portable Amps: SR71, SR71A, Reference, D3, and MiniBox-E+

post #1 of 31
Thread Starter 
Today I spent a couple of hours comparing the following five (5) portable headphone amps:

oMiniBox-E+
oRSA SR71
oRSA SR71A
oXin Reference
oiBasso D3

I used a 160 Gb iPod Classic filled with Apple Lossless files, for a line out I use an ALO Six Shooter (6 strands of Silver wires), and for headphones an Ultrasone PROline 2500. For music I used Barney Kessel’s Corcovado (Quiet Nights) from his CD Autumn Leaves.



First I would like to make sure that everyone understands that the differences are not night and day. All and any of these amps are very good and would make any user happy. Furthermore the type of headphones, source, music type, cables, and yes your own ears will determine what you hear and what you would prefer. At the end of the day the each and every one of us should listen to truly be able to decide which is best for our specific application. If like me, you may find that keeping two or more of the portable amplifiers are not out of the question.

Another item is burn-in. I believe in it and thus why it has taken so much time for me to provide follow-up to my previous post. The SR71A has about 950 hours, shy of the 1,000 I was shooting for. The Reference has 550 hours short of the 800 hours which IMO the 22,000 uF cap needs, although at times I think that 1,200 may be the real number of hours to have in the Reference. The iBasso D3 as well as the MiniBox-E+ have well over 750 hours of burn-in.

One item of interest to many here is the type of batteries. Some believe that batteries with low resistance and slow discharge are best. To that effect both the SR71 and the SR71A were tested with Tysonic 200 mAh low discharge batteries. I need to get eneelops for the MiniBox-E+ and for the iBasso D3, for this test I used alkaline batteries. The MiniBox-E+ has a built in 18 volt battery so that is not easily replaceable.

The added burn-in has made the SR71A much closer to the original SR71. However I still hear a little better detail an air between the notes in the SR71. The SR71A does have a more in your face presentation as compared with the SR71 which IMO has a bit wider soundstage than the SR71A. The bass definitely has more impact in the SR71.

Next I compared the iBasso D3 with both the SR71 and the SR71A. IMO its soundstage is in between (although closer to the SR71). I also believe that its overall presentation is closer to the SR71, with just a tad less clarity and not as much air between the notes. Nonetheless it has a very nice presentation with the added benefit of a built in DAC, and lower cost.

When I compared the SR71 with the latest Reference I could not decide which one I like best. I found their soundstage to be on par, however the bass had a bit more impact and weight on the Reference while the SR71 was a bit more extended. Very picky on my part but that is what I heard.

Left for last the cheapest of the five (5) amps, the MiniBox-E+ (stock configuration, two AD8610). Well IMO there is no contest, this was the best sounding of all, it does what the SR71 and the Reference do but better.

So as of now with the Reference shy of its target burn-in of at least 800 hours (1,200 better) I would rank them based on the amp section sound quality as follows:

1.MiniBox-E+
2.SR71 tied with the Reference
3.D3
4.SR71A

Some have asked me if the amps are quiet or not via IEM’s. Yes, the only qualifiers would be:

1.The iBasso D3 volume pot was scratchy as you rotated it. Once in a fixed position I could not hear any noise.
2.I could hear some light noise with the SR71A in high gain and with the volume pot past 2 o’clock. If you are here you are DEAF, I see no reason to be in high gain pass 2 o’clock with IEM’s.

Some closing notes:
1.If you need a USB DAC get the iBasso D3, it is a bargain.
2.If you need to drive ¼” and 1/8” headphones get the Reference.
3.If you need extended playing times (200 hours per set of alkaline batteries) get the Reference.
4.You already know which one I think you should get for the best sound: MiniBox-E+
5.REPEAT: The differences are not night and day. So if you already have one of the 5 amps no need to go and buy another (unless you really want to )

I will update on this when the Reference reaches at least 800 hours (10 days from now) of burn-in. Possibly again at the 1,200 hour (4 weeks from now) mark.

PD: I have sent Dr. Xin an email to discuss if he can improve the treble extension and perhaps a bit more detail/clarity. He responded with: "Then you may try add the 1000uf cap I sent you, it certainly adds more details." I do not know if I will, need to think about it. Plus jamato8 feels the Reference sounds better w/ a 12,000 uF cap instead of the 22,000 uF. I have a few 12,000 uF caps by both Nichicon and Panasonic, need to think about that tweak as well. Man, so much to do and so little time to do it.
post #2 of 31
Interesting review, Miguel. Nice. I would love to compare the SR71 and SR71A - but it isn't going to happen - I don't have the SR71 anymore, and since Ray is basically sold out of the SR71A, he quite understandably doesn't see much value in sending me a review sample.
post #3 of 31
Great review Miguel, I enjoyed the read. I just ordered a D3 because I wanted a DAC. Now you make me want to add the MiniBox to the collection. The Mini was out of stock as of last Sunday.
post #4 of 31
I don't get it you rated a d3 above a sr-71a? Maybe the d3 is a HUGE jump in sq but I have a d2 and the sr-71a trounces it without even being fully burned in
post #5 of 31
Ever hit that magical 800 hour? Interested to see how it stacks up once its there.
post #6 of 31
Quote:
Originally Posted by hockeyb213 View Post
I don't get it you rated a d3 above a sr-71a? Maybe the d3 is a HUGE jump in sq but I have a d2 and the sr-71a trounces it without even being fully burned in
It is possible. Pricier/bigger/branded products do not equal to better quality than cheaper/Made In China products. And that has been shown multiple times in various cases on Head-fi.
post #7 of 31
well unless the d3 is the biggest upgrade in the world against the d2 I strongly disagree I just don't think he liked the sr-71a sound sig. I don't think most people who have both would put their ibasso on top I sure don't
post #8 of 31

Well...

Quote:
Originally Posted by hockeyb213 View Post
I don't get it you rated a d3 above a sr-71a? Maybe the d3 is a HUGE jump in sq but I have a d2 and the sr-71a trounces it without even being fully burned in
What one also needs to consider too is that...
the D2 and D3 are very different...see headphoneaddicts reviews.

The D3 has a much better sound, I dont know personally but everyone says its tops. I love mine!
post #9 of 31
Quote:
Originally Posted by paulybatz View Post
What one also needs to consider too is that...
the D2 and D3 are very different...see headphoneaddicts reviews.

The D3 has a much better sound, I dont know personally but everyone says its tops. I love mine!
Yes, the D3 is well above the D2 in how good it sounds, and they don't sound the same to me.
post #10 of 31
Just glad I picked up that MiniboxE+ a long, long time ago, and got a very good deal from Fang at the time. Will never sell it. I do love its sound, but I only use it at home. Just too big to lug around.
post #11 of 31
Quote:
Originally Posted by hockeyb213 View Post
well unless the d3 is the biggest upgrade in the world against the d2 I strongly disagree I just don't think he liked the sr-71a sound sig. I don't think most people who have both would put their ibasso on top I sure don't
You never know until you've heard it.
And with the way iBasso are going, they definitely could top a lot of amps with their speedy innovation. Heck. Even the T4 tops my Meier Headsix. And the Headsix tops the RSA Tomahawk and even the Hornet. And I won't be surprised if the T4 even tops RSA's new P-51 and the Predator. That's how far their capabilities are.
post #12 of 31
So you say the D3 is better then the D2 Viper or just the D2 Boa?
post #13 of 31
i don't have/listen to a d2 and d3 before but have you guys heard about d1? i remember i like d1 a lot. i'm sure i felt it was better then let say a tomahawk. too bad that thing was huge. twice the size of a sr71a, at least. anyway, d1 sound different than a sr71a. so it's kind of hard for me to compare
post #14 of 31
I think the D3 is better than either D2. the Viper with different opamps can sound good but the D3 is already there in sound quality and the Dac is very good. The dac is clean seems to shoot the music right through without coloring it.
post #15 of 31
IMHO, the D2 Viper with LM4562 in the main amp and LM6172 in the ground channel is extremely close to the D3 and Pico - all three have a similar sound.
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