Glad to see you're still looking for more info Howard!
Let me add publicly now a few comments I made to you earlier: Everyone should remember that as good sounding as the Meridian 504 may be, it is extremely limited purpose and very bare bones. There is no narrow IF bandwidth, nor is there the option of gradual high blend, or even standard high blend for that matter. The stock IF bandwidth, as noted by Larry Greenhill in his Stereophile review, is very wide, and while the tuner sounds great fed with an FM generator, in the real world it will work properly primarily on strong local stations, or distant blowtorch stations.
Re: The Halo -- single IF bandwidth with 80dB selectivity. There is simply no way to coax audiophile quality sound from this tuner compared to most any dual-bandwidth tuner. The narrower bandwidth results in excessive group delay in the IF strip which in turn causes excessive IM and THD in the recovered audio. Yes, you CAN do this, but it requires carefully hand-selected filters, prefereably multiple GAXX type with a 110kHz GDT bandwidth, and each with a group delay equalizer. Looks nice, but is blown away by many for about $50.
Regarding Don Scott: I INVITE DON TO REFUTE THIS PUBLICLY. I have been told that Don Scott does not own the Sencore SG-80 signal generator mentioned in one of his Stereophile articles. Further, I have been told that he does his alignments "by ear", which is unacceptable and impossible to do properly. I've been told that one of his "modified" units measured around 10dB channel separation. This is awful. I've never had a unit come in under 40, and have personally achieved up to 80dB separation at 1kHz on select tuners. (This required buying the two best FM stereo generators ever produced in the world, however). Further, I have read that one of the modifications he did completely ruined superb high end tuner. He places an ultra-narrow 110kHz filter in the *WIDE* IF bandwidth running the distortion to heck. Clearly, if he let this outd the door, he is not aligning and measuring his work. If you need modification done commerically, use Ed Hanlon at Antenna Performance Specialites. Ed does the audiophile parts additions right, AND aligns it right. I wouldn't doubt that a Don-modified unit can keep up with a Dynalab. They really aren't that good as tuners. They're essentially a very mediocre tuner coupled with a handful of audiophile parts an a gorgeous chassis. Whoopee. And *TUBE* output stages? EXCUSE ME? This is the dumbest gimmick ever, and in a recent Hi-Fi Magazine article I read on the MD-102, the tuner was specified as having .1x% THD and something like 1.6% for the tube stage. Great concept: Even if your tuner is good, why not put the worlds crappies tube output stage into it to juice up the sound with a little extra THD? Stupid. Why not use an AD797 and be done with it?
I'm sure I've managed to tick off a few more people, but these are just my opinions, and I invite anyone to respond who feels like it.
Regards,
The Halo is single bandwidth