Hi Av_enthusiast,
I live in Hong Kong myself, have lived in Taipei (which was 110v, actually), and have been in Singapore for periods of a couple months in the past on assignment. I moved here from NYC about 5 years back and can relate.
Gear in Asia is indeed much more expensive compared to the US for US BRANDs. European/British brands are harder to say, as those run quite expensive in the US as well. In Hong Kong the premium ranges from 20-50% depending on what US brand in particular you are looking at. Singapore looked similar although I have never really purchased a full blown set in spore, mainly window shopping. Dealers are also more difficult about giving discounts here due to the small market, in fact most shops list at "MSRP" prices some 30%+ higher than the US, then cut 20% off and act like you are getting a phenomenal deal.
Due to the significant price differences, you will actually find that there is actually an extensive culture of parallel importing here, despite the risk of no warranty attached to that.
All in all, you will need to think it through and decide which method carries the most merit for you. Some food for thought for you:
- If you buy your gear in the US and bring it out here, usually warranties are enforced by original dealers. So much like parallel imports, you are likely to find it hard to get service, as you will have no relationship with the dealers out here and they will be out to get a leg and an arm out of you if you do need service
- I would not really recommend you bringing analog equipment out here. Someone mentioned turntables. I do not know the technicals, but another friend of mine had analog gears turn out very badly when he was trying to run them with transformers.
- If you buy your gear out here, you have the option to sell your old gear in the US first. It will be much easier and safer logistically for you to sell your old gear while you are in the US. This will help fund Asia purchases as well
- Similarly, if you are looking to buy second hand, its going to be easier for you in the US. second hand markets in Asia are smaller.
Selection-wise, you can honestly get most brands out here that you would want. I do not believe the brand selection is inferior to the US if you throw in British and European brands, which are harder to find in the US but easier in HK/SG. The prices just aren't pretty, because each city will have just one distributor dominating the supply. What with the strong population representation in Mainland Chinese and expats out here, prices aren't like to go down either.
All in all, you could definitely save a lot of money buying in the US and carting it over. But if you are out here in the long haul, I would seriously consider buying your stuff here despite the price premium to get acquainted with a few local dealers and the market.
To further address your specific questions...
1. Some factories/manufacturers are able to adjust their equipment in the US. There is a fee involved and can take significant time with shipping back and forth. Some audio-grade power conditioners also provide both 110 and 220v outlets, which would interestingly allow you to bring gear as is if you do not want to upgrade.
Some gear is also universal power supply, such as gear with a switching power supply.
2. I have been told 220-240v is usually the superior for amps at least. You can probably research why, I do not recall the reasons off the top of my head, it was actually explained to me by a dealer in the US so it should be legit, but I would imagine marginal or you would see more discussion about it.
3. Not familiar with this particular issue
4. I've auditioned both, but do not have extensive experience as I was in there for the 802d. I thought the 804d (new) was a little better than the 804s (old dealer demo being sold off) dynamically, bringing out the individual lines in the music more clearly. diamond tweeter is always nice on paper but I do not that think that was the cause.
That said, a friend of mine had 804s for quite awhile and was quite happy with them. The simple answer is if its bang for buck, the 804s is definitely better. But in absolute terms, the 804d is capable of more technologically. If you want to save money, 804s will serve you fine.
Good luck