Size matters. Bigger speakers reproduce lower sounds much better. All speakers roll off in loudness as frequency gets lower, and due to physical size there is a limit as to what volume a speaker of a given size can drive a sound at a given frequency.
As you turn up a small speaker its inability to produce lower sounds becomes even more pronounced. 'Piercing' as you say. A small speaker can produce those volumes at high frequency, but not low. This is why you can get 160db out of a small 1" dome speaker, but only as a piercing screech. To get that at 50hz you'll have a speaker the size of a shopping cart.
A larger speaker paired with a big enough amp will have a much easier time driving all frequencies over your noise floor. So it will sound balanced instead of piercing. Just a bigger speaker won't do it though. It needs more power as well. It takes far more energy to make low frequencies loud.
Edit- If you want something loud and cheap and don't mind plugging it in, look into gaming computer speakers. I have a set of these guys at work and they fill up a large room pretty easy.
http://www.bhphotovideo.com/bnh/con...U-_ewaAtjq8P8HAQ&is=REG&ap=y&m=Y&A=details&Q=