In today’s article and video we’ve got two classic salon grand pianos that duke it out literally every single day in piano showrooms around the world – the Kawai GX2 vs Boston GP178, which are two of the most popular 6-foot professional quality pianos in the world (both measure just under 6 feet at 5’11”.)

We’ll be doing a grand piano comparison with regard to how they feel and sound as well as looking at the similarities and differences in terms of their designs. Odds are if you’re looking for a 6-foot grand piano with a budget of around $40,000, you’ll have both of these pianos on your shortlist. Let’s start with some background information.

Kawai GX2 vs Boston GP178: Brand History & Information

Let’s start with what might be the worst-kept secret in the piano industry – both of these pianos are not just made by the same company, but they are actually assembled on the same production line in Hamamatsu Japan.

Boston as a line is of course owned by Steinway and sold through their dealer network. Steinway had some influence on the overall design of Boston pianos and there are a few components in common with New York Steinway’s that wind up on the Boston’s.

All of the assembly, construction and many of the materials actually come from Kawai, and as mentioned, Boston’s and Kawai’s are put together on the same production lines. While the marketing literature is pretty vague about this detail, anyone who has ever visited the Kawai factory can attest to this, as many of our staff at Merriam Music have over the years.

If you happen to be looking at either piano in a showroom, there’s a good chance dealers are going to steer the comparison towards the brands themselves rather than a technical comparison and breakdown, but we’re definitely going to cover that here.

Let’s move on to a conversation about how these pianos sound.

Tonal Comparison: Construction and Piano Sound

Kawai GX2 Soundboard
Kawai GX2 Soundboard

The GP178 has a larger soundboard than the Kawai GX2 as a result of Boston’s “wide tail design”. This design increases the overall surface area of the soundboard, though this approach can sometimes be at the expense of the bass register which can lack a tight bass sound. Fortunately, the scale design has been done really well so we’re not hearing any issues with the bass register.

Overall the GP-178 has a nice open sound, but there’s not a lot of cabinet resonance or damper resonance going on. The GP178 generates a ton of fundamental tone, but there’s less nuance surrounding the tone compared to the GX2 which has less fundamental, but more cabinet resonance, likely primarily due to differences in cabinet materials and design.

This is somewhat ironic because the GX2 actually sounds more like a Steinway than the Boston does as Steinways are really known for their warmth.

This warmth we’re hearing is from the use of Maple – there’s a ton of hard-rock Maple in a New York Steinway. When maple gets resonating, it has a distinct character and the Kawai GX2 also uses a high amount of Maple hardwood content in its Konsei Katagi rim, which is the part of the piano that contributes most to creating the cabinet resonance.

Back to the GP178, thanks to all of the direct soundboard tone, it’s effortless to generate power, even if you’re not feeling as much cabinet activation. The sustain is very good, though it seems to go on a little bit longer on the GX2 due to the cabinet activation.

Both pianos have a very colorful sound, and a big part of this is the vertically-laminated bridges that both pianos possess. This feature trickled down from the handmade Shigeru Kawai series, which was mimicked from the Hamburg Steinway.

In terms of the bass sound, the GP178 has more of a bite on the attack of the note and more of a bell-like sound. The GX2 has a rounder, warmer bass tone.

To our ears, the GX2 is doing a better job on the ‘break’ or transition area where the string material changes – a notoriously problematic area for piano makers.

We’ll cover the action in more detail below, but a quick note on action now as it pertains to sound; the keybed feels slightly deeper on the GX2 which equates to a greater degree of lower dynamic control. The GP178 is so easy to get firing, which is satisfying in its own right, and some people will prefer that.

Moving to the top few treble octaves, the tonal differences really start to disappear. This makes sense as we see fewer design differences in this section of the pianos – both have duplex scaling for instance – and very similar string tensions.

That’s pretty much it when it comes to the conversation on sound. To summarize, the GP178 emphasizes the fundamental pitch, while the GX2 has more warmth and cabinet resonance. Onto the action.

Grand Piano Action: Feel and Response

Kawai GX2 Millennium III action
Kawai GX2 Millennium III action

Much of the sales rhetoric you’ll encounter if you’re considering both of these pianos is related to the action. You’ll find the same thing if you’re looking at a Yamaha piano as well wherein Kawai gets trashed for using ‘cheap plastic actions.’

The fact is, Kawai has been using synthetic materials in their actions for decades now, and the response has been acclaim from players, and praise from technicians for how well they hold up over time.

Today, Kawai is using the same general action (with different levels of refinement) across their less expensive GL series grands, the professional quality GX series, to the handmade Shigeru Kawai lineup including the world-class SK-EX concert grand piano.

That said, despite the fact that any industry debate on the subject is long over, you’re still going to run into salespeople shooting darts at Kawai for their use of synthetics. At the same time, Kawai goes the other way and concedes that sure, they build Boston pianos, but they use an inferior action in the Boston pianos, reserving their premium Millennium III Action with ABS-Carbon Fiber for their Kawai pianos.

Ultimately, both the GX2 and GP178 are receiving very solid actions, though they do play and feel different.

Here’s some factual, objective information about both of these actions; both are assembled and built fully by Kawai. There’s some ambiguous language that Steinway likes to use that calls this into question, anyone whose been to the Kawai factory can confirm that Kawai’s craftsmen build and assemble the Boston actions from the ground up, based on a design from Steinway.

Despite their different designs, what’s interesting when you peek under the hood is that both actions actually share quite a bit in common. For instance, the action rails and keyframe are very similar if not the same between the GX2 and GP178.

Both action rails are mounted on hard-rock maple dowels which are anchored into a piece of solid supportive steel underneath. This is a feature that speaks to the solid craftsmanship both acoustic pianos are receiving. Both actions also utilize Mahogany hammers.

Kawai GX2 Hammers
Kawai GX2 Hammers

Now let’s look at some differences. One of the key differentiators aside from the action material itself, as the GP178 is using wood for the action parts versus ABS-Carbon Fiber on the Kawai GX2, is the key stick length. The GP178 has a standard key length for a 6-foot piano, whereas the GX2 has an extended length key that resembles the length typically found in a 7-foot piano.

The idea behind a longer key stick is to allow the player a greater level of control – a longer lever equals more leverage. This is the main reason that the keybed feels deeper on the GX2 than the GP178 and why it’s easier to play at lower dynamic levels on the GX2.

That said, the Boston GP178 overall feels very fluid and very satisfying to play, it just doesn’t offer quite as much control, and also happens to feel lighter. If you like a lighter action, you’ll probably actually prefer the feel of the Boston GP178. If on the other hand, you’d like to be able to dig in more and exact more control, the GX2 is better going to facilitate that.

Both actions have synthetic key surfaces to simulate the feel of ivory on the white keys and ebony on the black keys (Kawai refers to theirs as the exclusive Neotex surface.)

Other Components/Features: Materials, Construction & Finishes

Kawai GX2 Dimensions
Kawai GX2 Dimensions

At this point, let’s look at some other parts and components of both pianos and see where they are similar and where they differ.

Both pianos feature tapered solid spruce soundboards with a very high grain count, meaning we’re talking about slow-growth spruce here – the older the spruce, the better it transmits energy.

Neither Steinway nor Kawai reveals in their marketing literature whether the Boston soundboards are supplied by Steinway or simply the same soundboards as what Kawai is using in the GX series, but from what we can tell they do appear the be the same.

The beam structure underneath both pianos is quite similar, and the joinery from the beams to the inner rim appears to be the same. The GX2’s rim is slightly thicker. Both pianos have multi-laminated pin blocks, as well as brass agraffes.

You’ll find soft fall fallboards on both pianos, as well brass lid props, and hard finish music desks.

Some areas where they differ have to do with a few innovations that Kawai has incorporated, including a steel-reinforced keyslip, V-Pro plate, and what they refer to as their Stretcher Over-lap Integrated Design with an extra thick stretcher bar. All of these features are to support the GX2’s tuning stability, though the GP178 has equally good tuning stability as far as we can tell.

Both pianos are available in a variety of finishes, you’ll find them most commonly in polished ebony.

A potentially important difference comes up regarding the warranty; both pianos come with 10-year parts and labour warranty, Boston’s warranty is applicable to the original purchaser owner, whereas the Kawai warranty is transferable.

If resale value is important to you, having a transferable warranty is a big deal.

Final Thoughts

What kind of showroom do you have to visit to demo these pianos?

In North America, Boston is exclusively retailed through Steinway’s dealer network, whereas the GX series is sold through Kawai’s dealer network. Most major cities are going to have both a Steinway and Kawai dealer, however finding a Kawai GX2 and a Boston GP178 side by side in the same showroom may be quite difficult.

In Japan, however, Kawai’s and Boston’s are retailed side by side, which is certainly much nicer for the consumer. In North America, you will have to do some driving around if you are making comparisons.

And ultimately, despite being made on the same production line by the same people, these two pianos do offer different musical experiences that will definitely speak to different people. Be sure to check out the video for some playing examples to hear for yourself!