My Denon AVP-A1HD doesn't down convert to 2ch for the HEMC and neither does my Lumagen so I tried a couple of the cheaper converters on amazon (UK based btw) and they didn't work for the HD codecs unfortunately.
Bought the Atlona unit and it works brilliantly so I would definitely recommend it for the ease of use to be honest. It works for all the codecs I have.
I don't know of any other unit that does it that was available over here but the US may have other options?
Hope that helps.
Cinema Room: Denon AVP-A1HDA, Lumagen Radiance XE, JVC HD100 PJ + Schneider 2.35 Lens, Acer H9600BD 3D PJ, 8' wide 2.35:1 Screen, D-Box, Crowson Transducers, Parasound Halo JC-1, Halo A23 x 2, Chord SPM1200 x 2, B&W 802D + DS8 + SCMS, SVS PB13Ultra x 2, SVS ASEQ, OPPO 93, Nvidia Shield, SKY HD, PS3, XBOX One X, HTPC