Originally Posted by Bob A (SD)
After almost 4 hours of charging as recommended by David, I started evaluating the little gold standard gain amp. I used the HD580, K81DJ, and E2C with my laptop, Samsung YEPP DAP, and Philips portable CD Player. Absolutely no evidence of hiss with a nice black background. The laptop line out followed by the CDP and DAP respectively provided decreasing input level capabilities to the LDM+. The DAP ouputs only 20mV into 32ohms. I had to use about 90% of the DAP output with the LDM+ set to max to drive the Senns to loud listening levels. The CDP and laptop in combination with the LDM+ easily drove the HD580s with plenty of headroom to spare. So as speculated earlier in this thread it does take a specific minimum input to the LDM+ to handle the more difficult higher impedence cans. My Samsung YEPP DAP's output probably hovers at or near that minimum. But even with settings as cited the sound is crisp and clear which reflects well on the not fully burned in LDM+. The K81DJ and E2Cs were easily handled by the LDM+ with low to moderate input and moderate output level settings.
What I haven't done yet is to compare the LDM+ to my old Headroom Supreme and to the sources unamplified with each of my transducers. That said, I haven't found evidence of any overt coloration or frequency response skewing. The LDM+ thusfar doesn't seem to present a personality of its own. That's good
These are but initial impressions of a newly received amp. As it settles in we'll see what the bottom line is
Okay, it's been several months and a lot of hours since I received the LDM+. It has proved to have been a very good investment as it works quite well with my modified HD580s hooked to my laptop. It may be heresy but aside from the spatial circuit in my 14 year old Headroom Supreme, I don't find a whole lot of differences. From my knothole that says a lot about the LDM+. So frankly the Supreme doesn't see much use as it resides plugged into AC power with my bedroom system that rarely calls for can use. Its bulk, especially with the external battery pack, long ago caused me to go portable with it less and less.
I don't use the LDM+ with my tiny DAP-K81DJ combo as (1) that rig is dedicated to the gym, (2) the DAP output drives the AKGs sufficiently, and (3) the extra bulk is unwanted in that environment. I must amend my earlier comments because as the LDM+ broke in I no longer needed to use as high an input level from my Samsung DAP. Go figure as I hadn't read any comments about this sort of thing before. My Shure's no longer see a lot of use since the AKGs were acquired either although I did find that again the little LDM+ worked quite well with them. I don't use either headphone amp and/or cans with my main stereo or home theater systems (described in the link in my signature block below). But darned if this inexpensive little amp doesn't make my laptop listening fun!