I am going to buy a digital piano and now struggling between Roland FP3 (no built-in speaker) & Yamaha P120 (with built-in speaker). Originally, I preferred Roland more and planned to connect it to my home HiFi system (tube amp + ProAc speaker) instead of buying another set of studio amp/speakers. However, the salesperson told me that I have to be very careful for the level of volume since those ordinary Hifi speakers are not built for such purpose. It would be easily damaged by the strong bass/low frequency notes from digital keyboard(although I think there is also a lot of strong bass from many CD titles for the case of normal CD listening scenario). While STUDIO speakers are designed for such purpose and could stand strong punch even for prolonged usage.

Primarily, I would play piano at home and it would be fine as long as the volume is similar to that of acoustic piano. I am not sure if I really need to get a extra set of Studio amp/speakers. Any idea?

Hi Waff
The problem is not so much the frequency range (bass/treble) as the level of output from the keyboard. Even a CD player with variable outputs has a relatively low output level. Causing the preamp in your hi-fi system to overload can cause damage to home audio speakers.

SteveY,

Thank you very much for your reply. Do you mean the output level of digital keyboard is relatively higher than that of CD player? If this is the case, could I simply lower the volume level but yet make the actual loudness output from speaker comparable to that of CD player.

Just let me know if I have made any misunderstanding here. Thanks.

I own a digital piano and I have it connected to a hi-fi system. I haven't got any problem.
In order to not have problems with the speakers I set the keyboard's volume very low and I turn the volume down and up with the hi-fi system's volume.
I hope this helps!

One thing you should be aware of when hooking up a keyboard to a hi-fi system, the impedence may be different. While this may not seem to be a problem at first, but over time a mismatched impedence may "load" the preamp, causing damage. Lowering the volume does not change the impedence. You may notice on some amps or special effects that there is a guitar input and a keyboard input. The difference in impedence between these two is quite large and can cause problems over time. You might also notice a difference in volume, dynamics and clarity. There are devices to balence the impedence going into a mixer/amp/effects unit, but whether this whould work for a hi-fi, I really couldn't say. You might check with the hi-fi manufacturer for their recomendation.

Great post Shadorunnr! If it were me, I'd look into purchasing some inexpensive powered monitors such as those made by Boss (Roland) or Audix. They sound great, and will save your home stereo system.

I also think you're only looking at a few dollars more for the powered monitors than an impedence matching device to allow use with your home stereo.