I haven't heard the Apollo or any of the current Cambridge Audio models, but I'll chime in on the Music Hall. I bought the original 25, almost new and pretty heavily modified, a little over 3 years ago. I listen at least 3-4 hours a week, sometimes a lot more, so this player has seen a fair amount of use. No breakdowns or operating problems whatsoever. For the last year, it's been used as a transport only, but it's the transport and laser reading that usually cause problems. On the other hand, some Apollo owners have encountered disc reading problems that has been attributed to the unit's software. Search the archives and you can get more information about it. I don't know if the problem has been fixed.
With the Music Hall, you also have the option of having Underwood modify the unit to bring it closer in quality to the Apollo for approximately the same price. Sorry I can't comment on the sound of the Underwood mod, because my unit was modified by another company, no longer in business. In addition, my mod eliminated the op-amps, so its sound could be quite different from the modified Underwood unit.
With the Music Hall, you also have the option of having Underwood modify the unit to bring it closer in quality to the Apollo for approximately the same price. Sorry I can't comment on the sound of the Underwood mod, because my unit was modified by another company, no longer in business. In addition, my mod eliminated the op-amps, so its sound could be quite different from the modified Underwood unit.