If you start messing around with a succession of little boxes each solving one particular problem then things start to get messy and complicated. The chances of the system working reliably long term diminish considerably. I'd also listen to Sam Gangee's advice about loft temperatures.
Anyway, you're not the first person to face this sort of conundrum. Like most DIY'ers you've got so far in to the projector and hit a bit of a brick wall. What looked like an easy and cheap little project is turning out to be a bit more complex and pricey that you'd first imagined. Where you stand now others have stood in the past, so what I'm about to give you is the collected wisdom based on solving the same issue many times over for others. We are cutting to the chase rather than going all round the houses with the "
what abouts" and "
what ifs" when someone in your position starts to look at the weird and wonderful gadgets available via the web.
You have four practical solutions:
1) A conventional stereo amp with remote control + a DAC (optical to analogue stereo converter) +
IR repeater kit
2) AV receiver (with built in optical input) + IR repeater kit
3)
Compact Class D amp with IR control and Optical input + IR repeater kit
4) A simple stereo amp or AV receiver with analogue input + cable to connect the TV headphone output to the amp which then solves the volume control issue
Pros and Cons of each
For solution 1)
Cons are
cost: You have to find a stereo amp with remote control. That's easy with new gear (at a price) but harder with used gear unless you go for the sort of mini/micro/midi-sized CD/Radio stereo systems rather than a proper 2ch Hi-Fi amp.
Size: You'll need to hide the amp somewhere.
Cabling: You'll want to carry the signal as optical for as much of the journey as possible to avoid interference, but Optical cables are only available in specific lengths, so you might end up with either too much cable sat in loops or a couple of opticals and a joiner which is a potential weak point.
IR kit cable lengths: You might have to spend a bit to get an IR repeater kit where the cables are long enough to cope with the job.
Pros are
simplicity, audio power (current rather than wattage which is actually more important anyway, but this is only really applicable to proper Hi-Fi amps rather than CD/Radio stereo systems), and potentially in the
sound quality, but it's debatable whether you'd hear an appreciable difference in sound quality if the speakers aren't up to it.
For solution 2)
Cons are
Cabling: The optical cable length.
IR kit cable lengths, and possible
complexity of the amp (source selection, sound modes etc) when being controlled out of line of sight, and the
size. An AV receiver will be the biggest of all the boxes to hide. The
Pros are
Cost and the
Availability of suitable amps. There's a far greater choice of used AV receivers that tick all the boxes than there are Hi-Fi amps.
Power - second only to proper 2 channel Hi-Fi amps.
Features: The built-in Optical input and DAC removes a potential failure.
For solution 3) the
Cons are
cost: You won't find many of these on the used market so a new purchase may be the only option.
Power: This will be the least powerful of all the options so this amp will be working harder more of the time and that affects long-term reliability. It also means you need to exercise discretion with the volume control because distortion kills speakers.
Features quality: Despite being fitted with remote control the performance of the IR transmitters in the handsets for these type of budget devices is notoriously poor. The handset will have limited range and a narrow angle where it will work even when the amp is in direct line of sight. The
Pros are
size and simplicity - one small box which is relatively easy to hide handles optical directly as well as providing power.
For solution 4 the
Cons are
size again and the
technical issues of whether the source TV has a headphone jack and whether the output from it is controlled via the TVs main volume control of a buried sub menu that is harder to access. The other issue is the
quality of the cabling. It would be very easy to buy an off-the-shelf audio cable and find that you suffer with hum problems. The reason would be the cable's inadequate shielding. It isn't enough just to have "shielding" without knowing what the design of the shielding actually is. Not all shielding is created equally. Unfortunately very few cable retailers know anything useful about what they're selling apart from a few headline features. This goes equally for high-end sellers as it does for budget cable retailers. If you select #4 as your solution then get in touch and I'll sort you out with the right cabling.