The final step is to "calibrate" your ears. Listen to recordings of solo piano. Listen to what you enjoy, be it jazz, classical, or ragtime — just listen a lot. For part of this listening, use the headphones you bought for your digital piano. This will embed in your head, as a benchmark, the sound of high-quality acoustic pianos. One of the great things about digital pianos is that if you love, say, honky-tonk piano, all you have to do is make sure the instruments you're considering have a Honky-Tonk setting. Then you can "change pianos" at will. But for the moment, listen to the best piano recordings you can get your ears on.
When you start to audition instruments, you'll become aware that some of what you're hearing isn't the instrument, or at least not what the instrument is supposed to do. Part of what you'll be hearing is the result of room acoustics and the instrument's placement in the showroom. If there are a lot of hard surfaces nearby — uncarpeted floors and large windows — the results will be different from what you'll hear in a "softer" environment, such as a carpeted living room with drapes, bookshelves, and upholstered furniture. Placement in the room will also affect the sound. If you're serious about buying a particular instrument, asking the dealer to move it to another part of the showroom isn't an unreasonable request. Another thing to be aware of is that the voice settings of most digital pianos include some degree of reverberation. This isn't a bad thing, but it's worthwhile to listen to the piano voice, and any other voices that are important to you, with the reverb and all other effects turned off. This will allow you to judge those voices without any coloration or masking from the effects.
Evaluating Tonal Quality
Almost by definition, evaluating an instrument's tone is very subjective, and judging the tone of instruments that have a lot of voices can be overwhelming. Your best bet is to select the five or six instruments you think you'll use most and make them the standard for comparison as you shop. If you choose the piano on which those voices sound best to you, it's likely you'll find the others satisfying as well.
Digital pianos are really computers disguised as pianos, and the engineers who design them strive to develop a set of sounds and features unique to their brand. Like some features of a PC, many of the capabilities of digitals are hidden from view, accessible by pressing a sequence of buttons or through multi-screen menus. While the owner's manual will explain how to access these features or sounds, it's impractical for you to study the manuals of every instrument under consideration. Enter the salesperson! This is one of those instances where a well-trained salesperson can be invaluable.
Most manufacturers arrange trainings for their retailers' sales staffs, to enable them to demonstrate the relative advantages of that brand's features. Even if you're a proficient player, having a salesperson demonstrate and play while you listen can be a valuable part of the evaluation process. But remember that the salesperson is not going home with you! Don't be swayed by his or her talent — a really good player can make even a poor-sounding piano "sing." Focus your attention on the instrument itself.
You should make sure that you get the answers to a few key questions, either through the salesperson's demonstration or your own experimentation: