It depends on the efficiency of the speakers, stated in decibels. This information is only sometimes listed on websites, and you may have to go to the manufacturer's website and read the tech specifications. Bigger speakers tend to be more efficient, bookshelf speakers are usually around 84 - 87 dB. For decent sound with a 3 watt amplifier, you need very efficient speakers, around 94 dB or better. This is hard to find for bookshelf speakers. After a long search, I ordered a pair of Klipsch R-15M bookshelf monitor speakers that have a claimed efficiency of 94dB. This may be the actual efficiency, or may be slightly fudged like every other specification in audio. You can help by using at least 16 awg (gauge) speaker wire on relatively short runs (10 - 15 feet), but refuse to get suckered by the insanely expensive specialty wire they try to cram down your throat at nearly every audio store. Instead, get Amazon Prime speaker wire that is very reasonably priced and will do the job.
Lastly, there is a placebo effect in audio. Many enthusiasts doggedly believe that the more money they spend, the better sound will be. At the high end, you can easily spend $50,000 or more on specialty components for that audio 'pop'. If I had that kind of money I would feel guilty buying that kit. Also, since I've been around for a while and my hearing isn't what it used to be, the benefit would be illusory. Unless you're a musician with a fairly big income, it's a waste. Except for speakers. There is a definite increase in quality for speakers related to size and expense, but there are also many expensive speakers that cost a lot but don't deliver. So be prepared to spend most of your system budget on speakers, say 40 - 60%
Except for the extreme high end, the high fidelity audio hobby largely died in the late '80s. The audio magazines that reliably reviewed kit went out of business (computer magazines have too), and the web has not really picked up the ball.
Most people are satisfied with relatively crappy digital music recorded at low bit rates and have never heard decent high fidelity audio. But the digital revolution did give us cute kitten videos, and that somewhat makes up for it.