Kawai K-300 Upright Piano Review & Diapason Rating

The Kawai K-300 (122 cm) is one of the best compromises on the upright market: Millennium III action, a large soundboard and a mature tone. It is often cited as the direct rival to the U1 that wins on touch.

Who is it for?

For a demanding pianist after the best touch in the £8,000 / €8,500 segment — our quality favourite.

The action

The K-300’s headline feature is its Millennium III action, which uses carbon-fibre components in place of some traditional wooden parts. The result is a lighter, faster and notably precise touch: repeated notes and fast passagework come easily, and many pianists find it the more responsive keyboard in the segment. Carbon fibre also resists the swelling and shrinking that humidity inflicts on wood, so the action’s feel stays more stable across seasons — a practical advantage as much as a performance one.

The tone

At 122 cm, with a large soundboard for its class, the K-300 produces a mature, rounded voice with real depth in the bass. Where Yamaha’s house sound leans bright, Kawai’s leans warm, and the K-300 is often the choice of pianists who want a fuller, more singing tone for classical repertoire. It is a genuinely accomplished upright rather than a stepping-stone, and it rewards a player who listens.

Value against the U1

The K-300 is usually priced a little below the Yamaha U1 while arguably winning on touch — that is the crux of its appeal, and the reason the two are perpetually compared. The trade-off is the second-hand market: the U1 resells more easily and holds value better, so the decision often comes down to whether you prioritise the playing experience now or the resale security later.

Warranty and origin

Kawai’s longer warranty is frequently cited as a point in the K-300’s favour, and buyers should also check where a specific instrument was built, as production origin can vary by market and affects price. As with any acoustic, ask when the showroom example was last tuned and regulated: preparation makes an audible difference on an instrument at this level.

Who it suits

The K-300 is aimed at the demanding pianist who puts touch and a warm tone first, in the mid-to-upper upright bracket. Those who value resale above all may lean to the U1, but for playing feel the K-300 is our quality favourite in its class.

Frequently asked questions

Why do many prefer the K-300 to the U1? For its lighter, more precise Millennium III action and its warmer, rounder tone, often at a slightly lower price.

Does the carbon-fibre action need special care? No: it is maintained like any quality action, with the bonus of greater stability against humidity.

Origin, warranty and buying used

Two practical points deserve attention before buying a K-300. First, production origin can vary by market, and it affects both price and, sometimes, perceived value on resale — ask the dealer where the specific instrument was built. Second, Kawai’s longer warranty is a genuine reassurance on a long-term purchase and worth factoring into the comparison with rivals. On the used market the K-300 can represent strong value, since its slightly steeper new-price depreciation works in a second buyer’s favour; as always, have a technician confirm the state of the action and soundboard, and hear the instrument tuned and regulated before deciding.

Is the K-300 a lifetime instrument? Kept in a stable environment and serviced regularly, yes: the Millennium III action ages well and remains fully maintainable.

---

Our upright piano reviews

Compare our acoustic upright reviews rated with the Diapason method:

• Yamaha b1 upright
• Kawai K-200 upright
• Yamaha U1 upright

Field feedback: Yamaha U1 vs Kawai K-300: what owners actually say.

→ See all our Diapason ratings