First thoughts on my Practical Devices XM4
Oct 5, 2008 at 4:43 AM Thread Starter Post #1 of 13

fredpb

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I wanted a replacement for my aging Headroom Total Airhead (2AA model).
Wanted something below $200.

The reviews and shoot outs on this site were great.

I am very happy with the TA, but it's switches are iffy now. Great sound for me.

I chose the Practical Devices XM4. Added the optional opamp and the Lion rechargable battery system. Total cost, $180 with shipping from Canada.

Out of the box, without the fancy opamp, I was not impressed in the least. Certainly not worth the basic price of basic model of $135. No way.
But the optional chip was a BIG difference.

I am using the XM4 with an Archos 605 WIFI and Sennheiser HD580 headphones. The 605 does really have high quality sound. A bit bright, and not a lot of power. Buggy too. But I do love the 605, which also plays my videos from my Dish Network HD receiver. 80gb.

The TA with the 605 has GREAT sound!, with minor tonal adjustments to the 605.

The XM4 was a bit disappointing until I found the magic combination of buttons.

605: bass boost one "notch". Custom eq +4 db on lowest freq.
XM4: crossfeed circuit on.

This gives really good sound. Not as super as the TA (it has premium chip), but ok.

Really wanted a Hornet, but too pricey for me.

I use the portable system on my back porch in my SC townhouse. I spend hours a day out their with a drink, cigar, and my music.
 
Oct 5, 2008 at 6:00 AM Post #2 of 13
Pretty much the same thought crossed my head before I drop in the AD8620 on my XM3 (XM4 w/o the extra bits). They should have made AD8620 as their standard opamp if you ask me.
 
Oct 7, 2008 at 7:41 PM Post #3 of 13
I just got the xm4 myself last week. I really like it.. my only complaint is how touchy the volume knob is. I wear it velcroed to my ipod case and on my belt. The slightest bump turns the knob up/down. Any cure for this or not? Anyone else have that touchy of a knob? Thanks..
 
May 30, 2009 at 3:59 AM Post #4 of 13
I just came across this thread while looking up xm4 crossfeed. I'm using the stock xm4 without the 8620 driving some hd595s and was wondering if changing to the 8620 would help with the volume sensitivity/mid-range drop with crossfeed use.
 
May 30, 2009 at 6:01 PM Post #5 of 13
Interesting impressions, I have had the XM3 and XM4 and I found them quite nice. Specially so w/ the AD8620. I would burn in the XM4 for at least 150-200 hours before passing final judgment.
 
May 31, 2009 at 11:17 AM Post #6 of 13
I have both the 8066 and 8620 on the way to me now so i'll give them both a solid run. I have no intention of giving up this amp though, I love it already but just want to tweak it a bit if possible.
 
May 31, 2009 at 11:34 AM Post #7 of 13
As someone else mentioned, you need to give the XM-4 150 plus hours of burn in to pass real judgement. I like mine very much.
 
May 31, 2009 at 12:24 PM Post #8 of 13
Just did some rolling on my XM3 out of fun. AD8066 is good on revealing detail, but a bit lean on the lower end. AD8620 has better soundstage and fuller mid~bass. OPA2227 has a mid focus sound and isn't a bad choice either, but it just not as nice as AD8066 or AD8620. The original OPA2134 is just unspectacular in anyway. OPA275 is another one that works really well. It resembles AD8066, but even leaner and more revealing .
 
Jun 25, 2009 at 6:09 AM Post #11 of 13
I enjoyed my XM4 stock, but with the opamp upgrade to AD8620, it's a lot different (and better if you ask me).

softwight: I didn't notice any difference in volume sensitivity with swapping op amps.
 

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