I've been tempted by the descriptions of the Xonar in the past.
It's good to hear that it works well with the PM1
Your best bet is to check with Oppo and/or see user's manual [if cleaning is mentioned].
That said, I used diluted Fantastic spray cleaner. I sprayed the cleaner on a soft cotton cloth [an old tee shirt]--not on the headphones--just enough to get the cloth barely damp, then wiped the outside of the ear cups, the band, etc.
For cleaning the velour pads, I use clear adhesive tape turned inside out and daub it over the velour with a slight "rocking" motion.
For me, I prefer the (SS) Lehmann BCL, w/gain set to 0db [over the SS beta 22] with the PM-1. More detail, deeper soundstage, better natural weight to instruments/vocals, rounder/fuller bass. The BCL just seems to capitalize on all the inherent strengths of the Oppos.
Have not tried the PM-1 with the [hybrid] Fitz-improved Bada PH-12 yet. The Bada will be going to the repair shop this week [nothing from the right channel except a loud persistent hum]. ALL those 6SN7s and so little time! : )
I've used an Oppo HA-1, Schiit Asgard 2, Burson Soloist SL, Schiit Vali, AMB mini3 (briefly), TTVJ Millet portable tube hybrid (briefly), Peachtree Nova, iphone 5S. All sound great to my plebeian ears. OK, the iPhone is the weak link, but not that weak, which is one of the things I really like about the PM-1. They are one of the least particular headphones I've used, and one of the best sounding (to me, imho, ymmv.....). For those that need to feel they "scale up" with better equipment - they do, in that they do reveal the "betterness" of better equipment. The PM-1's themselves just don't require a fleet of high end gear to sound excellent *coughHD800cough* (I honestly don't have enough experience with the HD800 to take that shot at them, but I couldn't resist).
They sound better than one would expect (by a long shot to me) with an iPhone. I was pretty impressed with the Asgard2 pairing (Used a Bifrost Uber) and with the Vali (using the HA-1 dac output). My current is the HA-1 and the Vali running from the pre-outs of the HA-1 when I feel like a bit of tubes. The Vali is a killer little amp as long as you don't have to physically touch it while listening (tubes ring like crazy, even with a quiet vali). The HA-1 is a really nice, impressive all in one, but it exceeds "modest" in my book ($1,200 isn't modest to me.) As usual, beta tester caveat - Oppo gifted a PM-1 to the PM-1 group, and HA-1 to the HA-1 group, I was included in both. Yes, that very likely influences my feelings toward both pieces of equipment.
This may have been covered before, but I'd hate to peruse all 177 pages of posts (!). Anybody have the inner dimensions of the ear pads? If this is yet another set that will crush my earlobes, forget it. ;)
I get approximately 2-3/8" x 1-5/8" inside diameter and 4" x 3-1/4" outside diameter, giving a pad width of about 7/8".
My ears are medium-large and just barely make it all-the-way inside.
Oppo should be able to make/market a "roomier" earpad, building on the same "4-peg plug-in" base.
Or maybe they could just provide a blank base and let owners roll their own pads.
I prefer the lambskin pads, which fit me just right.
I'd say the PM-1 has great bass extension, but the PM-2 that I demoed didn't... The PM-1 definitely can satisfy bassheads, but there are bassier options out there.
The PM-2 has a very energetic and sweet midrange. One of my favorite parts of it, but the midrange is a little colder in nature.
Statements like this make me wonder if every PM-1 floating around sounds the same.
I eventually returned my PM-1 because I thought the bass rolled off too early and was lacking in power and impact, particularly at the lowest frequencies. I know I'm not alone in this impression, the InnerFidelity review noticed it, stating that "mid-bass and below seems very slightly loose, low in level, and rolled-off." Even the HeadRoom FR graph shows roll off starting around 100 Hz.
I'm no basshead and I wasn't satisfied, enough to the point where the bass was the sole deciding factor in the return. I see no way an actual basshead could be satisfied with these, assuming all PM-1s sound the same.
Just a few notes... The PM-1 is not a neutral can which means that it won't reproduce the original recording as close as possible... The majority of modern music is actually recorded unnatural, colder (and more fatiguing) than they should be unfortunately... To reproduce the original recording would reproduce all of that... Which is something that a natural/organic headphone (PM-1 as an example) will not do, rather it'll attempt to mask this which is actually preferred more on average nowadays ;)
However, it will give you the few dB higher than flat bass (and midrange) response you wish for which is more natural sounding, warmer, and easier to listen to. The PM-1 should not leave you wanting more bass on any circumstances really due to its signature. Note that this more natural sounding/warmer signature is what Olive and Welti discovered to be the preferred signature for most audiophiles, which is why it's enjoyed by just about everyone :p
With that said, I do agree with your impressions of the PM-1... The bass isn't lacking, and doesn't roll off that early, though it does have a slight low-bass focus that gives it a bit of warmth, thickness, and body. But it does have good depth despite the fact.